The problem is most of this stuff you listed is subjective, even if I personally agree with it.
For instance, Geno is 99.99% likely dead this game, his Mii is a silver bullet of sorts. But so long as Geno fans are respectful and acknowledge his shot is not great right now, why should they be gatekept from speculating on their character?
Fan rules are always concrete except when they aren’t. Sometimes, these rules are broken easily. Smash is no longer a Nintendo all stars game and hasn’t since November 2015. Ridley is not too big. Microsoft is involved with smash now. Many fan rules, such as no third party getting a second rep and then a second unique rep or spirits deconfirming, have been disproven.
Now, does that mean Waluigi for instance is a lock because ATs don’t deconfirm? Not in the slightest, but gate keeping like this is not good either.
If you speculate on chance, you can’t really gatekeep and you have to keep everything in mind. I run Rate Their Chances. We debate and discuss all sorts of characters for smash, and honestly we have had pretty good track records for the most part. We did say that Sephiroth as a whole was underrated before he got in, and said SNK was a dark horse. Our only real miss was Kazuya, mainly because everyone thought Tekken was dead after the Heihachi Mii. Part of the reason for our success is that we don’t gatekeep, people can nominate and bring up anything. Heck, people helped nominate SNK, Sephiroth, or Joker (who was revealed right before we would have discussed him in about a week.) Gatekeeping is bad.
Saying a character is unlikely is fine. For example I say Rayman is unlikely all the time. Saying people shouldn’t talk about rayman or support him is a different matter. If someone can make a good case for Rayman, I can respect it. Speculation is subjective, but you can’t throw objectivity out the window. Build your case for a character and why they are likely. Don’t gatekeep who others might think are likely or you might miss important points.