Why was MN Brewer's personal attacks not deleted and yet my reply to one of them was deleted ASAP??

MN Brewer's initial personal attack which was obviously aimed
at Obama supporters aka. "some DUers" was made
indirectly in a subthread started by me:
http://www.democraticunderground.com/discuss/duboard.php?az=show_mesg&forum=433&topic_id=717205&mesg_id=717323

I alerted on it, yet it remained standing.

Then MN Brewer made another personal attack in direct reply to
me:
http://www.democraticunderground.com/discuss/duboard.php?az=show_mesg&forum=433&topic_id=717205&mesg_id=717420

I also alerted mods to this remark, yet it, too remained
standing, despite the insulting use of the term
"Obamabot".  So I decided to reply to MN Brewer in
Reply #113.  When I checked back minutes later, my reply was
gone yet both of MN Brewer's personal attacks remained
standing.

This is what I said in reply to MN Brewer's attack:

"I'd rather be a fact-based Obama supporter than a
bile-filled PUMA like Jane Hamster Face or a right wing troll
paid by the Koch Brothers to astroturf progressive
websites."

Please tell me by what rationale did mods see fit to delete my
reply in record time while ignoring or discounting my alerts
to MN Brewer's very obvious attacks against Obama supporters?