Stealing may not be the right term, but we (the people mining at official merged pools) would get more nmc if it weren't for you, even if you pay out the earning to your miners.
Who gives a flying crap? If you can't compete then die. Sorry this is capitalism at its finest.
I don't use slush pool but your claims he took "your namecoins" or that "his hashes don't belong there"
are beyond pathetic. If your hashing power sucks so bad you can't compete then close up shop. The network doesn't need you (as in you the individual), it just need aggregate power. You aren't entitled to any monopoly of namecoins.
I I were a miner @ slushes I might be annoyed that he risked the stability of the pool for testing but that would be the extent of my beef. Still the idea that "his hashes don't belong there" just makes me laugh (not with you but at you).
As far as using test-net. Most of the issues w/ merge mining deal w/ large pool integration. It is kinda hard to find 100GH/s worth of hashing power willing to spend couple hours on test-net simultaneously for free.
Grow a pair and stop whining. If you think slush's test was bad just wait I predict within a month most major pool will be merge mining (because miners will flow to those who are from those who aren't) so you can expect 5TH+ more competition.