+++ This bug was initially created as a clone of Bug #576305 +++ Please declare the Compatibility Reporter as compatible with SeaMonkey 2.1.* on AMO. SM 2.1 RC 1 is expected today so the final is very close.
Hm, internally we already have support for SeaMonkey 2.2. See bug 649634. Not sure why AMO is listing the wrong max version. Justin, can you please check that? I do not have permissions to change anything for this add-on. Probably it would be helpful to add me.
The source code had maxVersion 2.1b2. I just changed it to 2.1.* for the next upload, r88711. I have also updated the maxVersion to 2.1.* on AMO for the current release (0.8.3).