Don’t get me wrong, it is definitely possible that the Speaker is a psion, but given the evidence that we have available it is just as likely that the Speaker is a thrall, or a dreg.
And all of those options are far less likely than the possibility that the Speaker is a Human or an Awoken or an Exo.
Just because there are multiple possibilities, that does not mean each possibility is equally likely.
So if it turns out the Speaker is a Psion I will say, “ok”, and I will be perfectly happy with it because there will be evidence. But until that day comes I will say “there is no evidence to suggest this over other, more likely possibilities”.