Well, the opinion of the community doesn't really matter here. You'd need to ask the tileset creator for permission, not us.

That said though, there's definitely a few tilesets on J2O that were based on others' tilesets without permission. Which is not the result of a conscious decision on the part of the J2O staff - I'm not a big fan of it myself. However, you should really try to get permission from Mez personally first.