Sorry for the delay.

The reason tempreject is happening is because devnull and permreject
didn't trigger for some reason.
I looked at the code for you, and the only reason I could find was that
isspam is not being set to 1 (i.e. spamassassin isn't flagging the
message as spam).
I'll admit that it's not super obvious, but sa-exim will not reject a
message, regardless of the score, if SA doesn't say it's spam
( X-Spam-Status: yes )
If you tweak your SA config according, things should work.

Admittedly, this restriction should go away: sa-exim should just not
care whether SA says it's spam or not, and only look at the spam score

Hope this helps.
Marc