Even worse than Luke-Jr promoting such attack is the fact that he's apparently, so far, "getting away with murderer". Depressive. It's as if lots of miners would collude with deepbit to reach >50% and start double-spending to their profit.
It's not quite the same because miner incentives are different. Bitcoin miners have an incentive to kill rivals, but double-spending would damage the value of their investments.
Ding ding ding.
51% provides an economic disincentive to use hashing power for "bad". That doesn't mean someone who doesn't mind destroying millions of dollars can't try but there is no ECONOMIC INCENTIVE to do so.
Starting a crypto-currency w/ merged mining WITHOUT large commitments from miners and pools (i.e. hundreds of GHs) is stupid.
Rushing a launch is stupid (from first post to genesis block was <24 hours).
Combined they created a situation where there was absolutely no economic disincentive. It was "free" to attack the chain. Essentially the blockchain's survivial was based on "everyone in the whole world being nice".