The ebuild for openmotif-2.2.2 was removed from portage some time ago, even though it is not completely replaceable with openmotif-2.1.*. libXm.so.3 (which is provided only by openmotif-2.2.*) is required by several commercial applications (e.g. Pro/Engineer and Realsoft).
I'm aware of the problems mentioned in bug #29388, but removing important ebuilds from the tree is not a good answer to any problem. The ebuild should be inserted back to the portage tree, and hard-masked if that's really necessary.
you can still fetch it from the cvs web frontend, if you really need it.