Because common courtesy would be to ask Foxer first.
Because if the "fix" doesn't fix anything (or worse), nobody can blame Foxer.
Because while nobody can prevent you from tinkering with someone else mod for your enjoyment, you aren't legally authorized to release it unless specifically told otherwise.
Because starting to modify his work seems innocent, but them someone else think he can do whatever he want with it, including releasing it under his own name elsewhere.
I get the common courtesy; should have asked first, ok.
Don't get the "nobody can blame Foxer." Is the danger that, because Foxer started the thread, people assume he has total responsibility for what's posted here? Alright, people can be silly sometimes, we'll accommodate the idiots. So the logical solution is to make a new thread and link it from this one, yeah?
Legal issues: don't see how distributing by PM mitigates this in any way. Is this an "out of sight, out of mind" thing? Yes, this is technically a rights violation - it doesn't matter which way you distribute.
Ditto the last point - don't see how distribution by PM mitigates this.
In conclusion, I see why permission should have been asked, and I see some
slight value in moving any edits to the files out of the thread started by the mod creator. So start a new thread - why use PMs?