I think this is OK. That's what you get for using a domain who does this 
sort of thing as your email provider.
Right.  But again, if I'm trying to find your key, I have no way to know 
how sleazy your mail provider is, so I have no way to tell whether to 
trust the keys they publish.
I do consider this proposal's handling of this case superior to the key
servers.
A key you get from the key servers might be real or might be bogus.  A key 
you get through DANE might be real or might be bogus.  What's the 
difference?  A key from DANE implicitly has an endorsement from the 
domain, but a key from key servers can have endorsements via WoT 
signatures.  In each case. unless you know the endorser, the endorsement 
is useless.
R's,
John