I wasn't that much clear because I assumed that it would've been enough but let me restate.
The following is assuming he would be an hazard.
First, that's a deconfirmation and Sakurai did all deconfirmation by telling a direct statement and mostly with picture/video. It already happened for too many instances so it's really obvious that he doesn't want to create speculation on them. But that makes the August 20 quote suspicious however, it's not clear what he's trying to tell. Not showing him until April 8 is again suspicious for how many time we saw the stage but again, it's not clear. In the direct, JUST AFTER describing an hazard in details and fully show him (this was even done before), we see a shadow of ridley on the same stage with Sakurai telling again double meaning quote so it's still again not clear.
Don't you see a patern? The only thing I saw from ridley is his tail which only tells me that it's other m ridley but not what he's doing here. Why it's not clear? I said earlier that it should be but what raise the red flag is the time gap. For MONTHS, we saw tons of pyrosphere pic and none of them has ridley in it so it doesn't make sense to see his shadow but not him. If he really wanted to deconfirm him, he would need to do so during the direct DIRECTLY (uhh... no pun intended) at the latest to stop speculation. Where it gets highly suspicious is that he did the absolute opposite: more speculation and you know why? by not being clear.
Looking at all the evidence, they are all double meaning so much that it's clear it was on purpose. But showing the shadow is counter-intuitive for an hazard since he wasn't showed before. What this means is that the shadow logically, shouldn't be there. The same goes for his quote since it couldn't have alluded him as hazard because it's double meaning and still not clear. They have no reasons to be there if he was an hazard but there's one thing left that do make sense to be there: Pyrosphere. So, it seems kinda odd that the stage is the last thing left that could tell hazard. It's the fact that we saw ridley's shadow on that specific stage that make a lot of people believed he was an hazard along with the quote. But because the shadow shouldn't be there, there's another reason on why this stage was on the direct. It turns out that it's the same stage showed and revealed on August 20. Not just that, but it's also on that date that Sakurai began to be ambiguous.
This is where the fun begins. How could that be coincidence? To reiterate, The pyrosphere stage was made to represent THE SAME LOCATION as you fight ridley AS A BOSS. AS SOON AS ITS REVEAL, Sakurai began heavy speculation for an unknown reason but it does mention that ridley could be there in some way naming him an enemy of samus's past which indicates that she fought ridley here before. Then, we show THE SAME stage multiple time WITHOUT any statement or image from head to feet for MONTHS thus, bringing even more speculation. Finally, we see THAT STAGE with ridley's SHADOW that doesn't belong here with a double meaning quote that TALKS ABOUT BOSS without talking specifically on ridley but again, that quote shouldn't be there. This situation, is WAY too convenient for this stage to be used with coincidences. The stage just HAD to be made and used for a reason. If the reason that stage wasn't because he was an hazard, as the other evidences shouldn't be there, then why it was there?
There's only one possible explanation that even explains the August 20 quote: it's ridley's home stage but since he isn't an hazard on said stage, he has to be playable.
This would means that the August 20 quote, the day the stage is revealed, was indicating that it was ridley's home stage because he mention how samus fought ridley on that exact location. Since he didn't even mentioned him, it created a mystery that hid the fact he was playable by being ambiguous and not referencing the hazard role directly thus, bring speculation. Then, to create even more speculation, he used the time in his advantage by making us wait for months while showing a good amount of ridley's home stage pictures but still not telling or showing anything clear so the mystery deepens. Finally, as speculation seemed to have increased because of the direct, he shows his shadow which suggest secret on his home stage for the ambiguity and a quote that isn't targeted to ridley but tells that there's other boss characters thus, dividing even more speculation which makes more discussion to increase the overall hype. Now, by not telling anything at E3 and not showing his home stage, he's using time again for even more hype but the shadow secretly revealed that he was playable since a shadow is usually symbolic of secret.
So, the fact that he's playable would explain everything Sakurai did. The hazard doesn't because the only evidence believed to allude to that logically shouldn't be there and it was the shadow.
As for when it will be revealed, either in a direct to blow minds or post release. Both are possible but I wouldn't find surprising for Sakurai to continue teasing him. Though, if it's post release, he's unlockable.
