It' not absurd. It's their private property. I'm not a creationist, but I wouldn't dream of going inside their property to mock them.
When I took a tour of Temple Square in Salt Lake City with my family I made an occasional discreet comment in a low voice expressing skepticism (I'm an atheist and the rest of my family is Deist in a vague sort of way), but never when anyone else could hear, and certainly not while we were being escorted by a young tour guide! It would have been rude. The only thing I commented on while touring The Vatican was the architecture & art. I would avoid going to the Creation Museum because of the effort needed to restrain myself from laughing out loud... ;-)
As absurd as the Creation Museum is, a small portion of this group seemed needlessly confrontational.