Do you think Aspies have a natural advantage at poker due to the lack of facial expressions?
Im not sure that Aspies do have a lack of facial expression. Maybe they do to some extent, but it is something which i had to practise at, though its not something i found difficult.
As far as it being an advantage..
If you can't maintain a 'poker-face' then you will not have much chance in most games worth playing in.
It's usually only beginners which have these sorts of tells, and you're going to beat them by outplaying them anyway.
There are other tells which players have ( even high limit players), but in general the theory of tells is overrated - it's not where the money comes from really.