TBH its unfortunate as its now put me off donating to such causes in the future though.
I'd do it again.
We don't know the reasons.
Are we sure the other Phil Miller is the same Phil Miller?
Maybe it wasn't as bad and was blown out of proportions and he is embarrassed?
....I'd do it again too. Every single case and person is different.
No, we don't know the reasons yet.
Yes, we can be 99.9% sure it is the same Phil Miller - Everything checks out (I could go into detail but please take my word on it).
Let's for a moment say that his accident wasn't as bad as we all think and that he feels embarrassed as you suggest: It isn't difficult to say something like "Hey guys, that's an amazing thing you have all done but there is no need, I am absolutely fine now, and so I suggest you either bung it into the Forum Fund or refund folks".
It seems so out of character as we perceive him for him not to respond at all, and so he's not doing his reputation any good by ignoring us. I think I have now lost total respect for him unless he reappears in the next day or so.