>so... why isn't there a command i can issue which
>would delete everything sent to the list from that address?

Maybe because nobody thought that ripping out
whole voices from the archives would improve the
usefulness of the archives for the remainder of the
group?

The whole idea of mailing list archives is to preserve
what is said, not make the logs into personal swiss
cheese at the whim of any random participant.

My welcome messages make it clear that, if you speak
(write) to the group, that message is before the group,
permanently, as part of the archive.