So a 9th level wish spell, was not powerful enough to close a portal, but was powerful enough to send a someone into the distant future.... (( while a typical cleshay of the spell, not a very wise use by GM, unless it is to kill off a character permanently )).
Oliver, you should read the wish spell description, and with some examples there, maybe you will understand my decision.
With regards to the OP, you decided to remove a character from the game because you didn't want the Wish spell to work. That's pretty bad GM'ing and if I were the player, I'd be pissed at you.
The player was totally aware that if he wished something too powerful, the consequences could be dire. I don't see how this is bad GM'ing any more than killing a character behaving foolishly by attacking an opponent too powerful for him. Unless you want that characters can do anything without any consequences whatsoever.Also, I didn't remove his character, I just wanted him to go through some trouble before he could eventually return. If I just wanted to remove his character, I would not have asked a question on how to make him come back by opening this topic in the first place.
Anyway, thanks to all others for contributing with good ideas and hints.
As for the character, he has found a way to come back now, with an idea similar to the one Kadance proposed. Thanks again.