If so, could people could react by making btc nodes that consider that rude behavior and begin blacklisting rude nodes wrt which block chains they consider accepted?
This is one of the proposed solutions. Basically centralize bitcoin by somehow whitelisting good blocks or blacklisting bad ones. The problem is this would require a change to _all_ bitcoin software. Meaning EVERYONE has to upgrade to this new centralized approach. Plus the decentralization of bitcoin is lost.
Pretty sure that solution would spell certain doom for bitcoin.
Gavin offered a solution which _might_ work [1]
[1] http://gavintech.blogspot.com/2012/05/neutralizing-51-attack...