Where is it legal to take large pieces of live coral? I think that our actions should be based on an understanding of what is legal. I think the flow chart of an appropriate response has a big diamond at the question: "is it legal"? If it is entirely legal, yet you feel it is inappropriate, then possibly you should make these people aware of your opinion.
My buddies were taking hundreds and hundreds of pieces of live coral colonies off a seawall in Key West a few years ago using hammers and chisels and collecting the coral. Would "you people" have flattened their tires or punched them out?
.
.
.
.
Wouldn't you have felt silly, if you instead politely asked them what they were doing and discovered that they were removing the coral prior to demolition of the seawall and that all the colonies were being collected for future transplant and the work was mandated by the government.