The word going out now is that in this case, it was not the romney campaign, but the 'christian coalition' (this year, for santorum) who tried to lock down the convention so they could get their people to the RNC. Since they didn't have enough people show up to the caucuses several months ago, they already knew they were outnumbered, so they added some rules at the last minute, such as 'the new rules are not debatable' and 'the chair is permanent and cannot be removed'
Here's some more of the events leading up to the police intervention. The delegates are asking about these new rules. If the chairman refuses to acknowledge delegates from the floor 3x, they can call to have him removed.
Louisiana Republican State Convention 2012 - YouTube