I totally get the OP's point. It probably comes down to what we consider, individually, to be reasonable rules of behaviour in society. I think what the 2nd dude did was weird - picking a table in an otherwise empty restaurant that put the two patrons directly in their line of sight when he could have chosen a myriad of others that didn't have the same result. But then again I'm not a terribly social person so expect myself and others to ensure our personal space is protected whenever possible.
I don't think it makes me or the OP weird, it's just our perception of what's "normal" (which is subjective since there's no rule book - oh, except about where to sit with your dude friend at the matinee).
The original post could have been by me!
It surprises, but then again, it doesn't, to see a number of people think this is okay. I too find it weird and intrusive. Depending on the situation, I move or leave. Not in a huff, just in a manner that simply says I've decided to leave. It creeps me out.
I don't mean this in a contentious way, and it is like the OP says, "it's like having a stranger come sit directly across from you in a booth", but is this really considered normal behavior that more 'outgoing' people do?
It seems needy and just weird. I've had it happen with men and woman (not the good looking kind).