It's a vague spec, and IE behaves differently than every other browser out there. It's vague enough that they added additional redirection codes (303 and 307).
I see your point. Although, I've been using 303 redirect for this purpose in my app after reading the specs, and haven't experienced any problems yet. So maybe you should consider switching to 303.
RFC 1945 and RFC 2068 specify that the client is not allowed
to change the method on the redirected request. However, most
existing user agent implementations treat 302 as if it were a 303
response, performing a GET on the Location field-value regardless
of the original request method. The status codes 303 and 307 have
been added for servers that wish to make unambiguously clear which
kind of reaction is expected of the client.
