Not really. The numbers are too small to mean anything statistically, and it isn't a proper random sample. The only thing you could say is that a little less than a third of people who know about one specific hardcore Smash tournament want to play PM.
I think you may be misunderstanding what you're seeing.
A person can sign up for multiple games, so it is almost certainly not the case that less than a third of the people want to play PM, it's more the case that people are least interested in Smash 4.
You're right though, it's just one example, though this is a particularly large tournament in Smash standards. However, I think you'll find this pattern mostly holds true where all 3 games are featured.
Having been to ALOT of events where all 3 games constantly exist (I have waaaaaaayyyyyyyyy too much free time) which involve both tournaments and just random play, I've not seen this to be the case, myself. It's typically the Wii U version right now that is played the most in such places, with normal Melee behind that.
Like I said, it makes sense. It's just much, much easier to A: know about, and B: acquire the usual 2 games. Not to mention that the U version offers proper online play; it's REALLY easy to get practice against actual opponents whenever you want to. It takes hardly any time at all to find a match. Both of the other games can be very iffy as far as finding opponents. It depends entirely on A: wether friends of yours are into it, and even then, that often means repetitive matches against the same players over and over, or B: the area you're in; my area has NOTHING as far as this stuff goes, as such, I travel to all different events or conventions or whatever they happen to be.
There was a short time when this was different, when the Play & Trade was around, the best damn gaming store ever. And then Gamestop, the evil behemoth, ate them. I cannot forgive their evil. After that happened, well.... I dont really buy physical copies of games anymore. Screw Gamestop. Ugh.
Of course, none of this stops the REAL problem from existing, which to me is Smash versus bloody Street Fighter. When it's in a place that has games from more than just one series (usually the case fro me), chances are, SF will be there, beating it out.... sigh.
I tell ya, that bit gets old really fast.
