From Sam Hartman:

... The advice in section 7.2 goes against the requirements of section 7 of
draft-ietf-behave-nat-udp (an approved BCP).  Even so, I think it is necessary
for GIST to do these things but I think we need to be very careful about the
interactions with other things deployed on the Internet. 

and specifically:

Explicitly call out this document's divergence from draft-ietf-behave-nat-udp.