I see.
So...those people (Adolf Hitler, Saddam Hussein, Osama bin Laden) were under threat of death, so they ran and hid. We can therefore conclude the sign is threatening the WI senators with death. Before you say "Affirming the Consequent," tell me what the sign is trying to do otherwise, except perhaps convey an implied Hasty Generalization?
And don't forget the accusations that George W. Bush abandoned his duties by fleeing to military bases instead of returning directly to the White House after the 9/11 attacks.
It definitely seems like a infiltrator sign, other than its format being similar to others.
The sign holder was implying the Wisconsin 14 are cowards, just like Osama, Hitler, and Hussein. Don’t read into the sign more than is there. Sometimes the simplest explanation is the correct one.