Listen I saw a post about the citizens of L'Manburg moving to Logstedshire (or whatever the fuck the name is) and having like, dual citizenship or something like that which makes me wonder... Yeah what is stopping them from doing just that? Dream said he has no problem with people visiting Tommy but said nothing about people staying with him? He's okay with Ghostbur being there basically all the time, right? So why can't the others do the same?
Another thing I just want to say is:
While c! Dream is a fucking asshole and I despise him with all my heart, I have to say that he's a fucking genius. Obviously he's exiled Tommy because he never listens to him, never bends to Dream's will (he said it, not me), so what's the next best thing for Dream to do? Breaking Tommy. He's been trying to break him for the longest time now, what with all the betrayals he put him through and yet, Tommy still stands. Why? Because he had his friends. He had Tubbo. But now? Now he's alone. Alone with the ghost of his brother, sure, but ultimately he feels alone, and he's starting to give up, to lose hope. And this is all that matters to Dream.
He doesn't really care about the others, not enough to constantly torment them anyways, because either they do nothing against him or do what he wants. The only exception was Wilbur, but he died doing exactly what Dream told him to do.
So he can't accept Tommy's stubbornness and refusal to listen to him. Tommy refuses to give him even an inch, even if it's while jokingly talking about being friends (and I'm still talking about the characters here, I know irl Tommy and Dream are good friends)! Dream will say something like "we are still friends, you know right?" and Tommy will stubbornly refuse until eventually one of them drops the argument or get distracted/go ooc.
This is what Dream can't accept: defiance. And what is Tommy, if not defiant?
Tl;dr: Dream mad cuz Tommy don't listen. Tommy stubborn little prick who doesn't give in
