I understand where he's coming from. It may be unwarranted, but it's not "ridiculous" per se. I think some of you are taking it the wrong way.
Think of it like this: Would you be happy if someone came out with an even better Smash mod than Project M just before 3.0 and destroyed all the hype you'd built up? For people not immersed in our community, I'm sure it can be hard to accept at first that something might be more fun than a game they've been anticipating. It's like a huge buzzkill, in a way; like when someone retorts to your happiness of an accomplishment with "Well, guess what I did that was even better?"
This guy doesn't want his hype killed, that's all. Or at least, that's how I'm taking it. Personally, while I understand I don't quite sympathize. I love Project M, but I am sure there's something about Smash 4 I'll enjoy. Perhaps not as much or for as long, but still. We don't even know much of ANYTHING about the game yet, so it's hard to judge.
My perspective is that each game has something that others do not. Even if Project M is technically "Brawl but more fun/better", there are some people who prefer Brawl's physics and the horrid tiers and thus less matchups to learn, etc. It is also an "official" game, which attracts a lot more players than a mod might initially do. Thus, there's a social benefit to playing Brawl over Project M for some, though for others those benefits aren't enough to warrant playing it.
I on occasion play Brawl, though rarely. I find that despite its shortcomings, it's sometimes nice to mix things up. Smash 4 will likely be the same.
To the OP, it is essentially up to you to decide what is best. Have confidence in yourself, observe the facts and what each game has to offer, and then conclude as to how much desire you have for both in an honest assessment. Sometimes, while it may be hard, you may have to accept that one thing will not have the content that the other will.
So basically, if you really want to try Project M, do it. Keep an open mind for Smash 4, and wait for upcoming information on the game that may pique your interest. I just wouldn't hold expectations for something that isn't known much about. Nor would I assume that Sakurai will go out of his way to please certain players.