Definitely. Your firewall/proxy has no idea what the heck the POST means
and doesn't know whether to allow or deny the thing. And don't say "look
in the body" -- that's very expensive for a firewall/proxy to do. Most of
them don't even try. The idea is to look at the HTTP method to figure out
what operation is intended.
The simple fact is that you can argue POST is appropriate for EVERYTHING.
"Hey! I'd like that page's contents. Why don't I send it a post and it
will send back the contents?" "Time to modify the page, let's just POST
the new content to it." "I wonder what metadata is on that page? Let's
send a neat little POST to get that back." Nevermind that the better way
to do these is with GET, PUT, and PROPFIND.
POST is your generic catch-all with zero semantic meaning. I would say
that you need to _justify_ using it, rather than continue to use it as a
default position which needs to be argued away from.