Trump claims he can use The Insurrection Act because 50 percent of presidents have done so.
In total, 16 presidents have invoked it. Since 45 different people have been president in the US, that is 33 percent, NOT 50 percent, and the act has not been invoked since 1992.
Previous presidents invoked it because they had the legal grounds to do so. Trump does not.
So this is an empty threat, because there is no insurrection, and if Trump invokes it, that decision will be tried in a court of law.