When most people think "funeral protest" they think of Westboro and the now-deceased Fred Phelps. In fact it has inspired laws against protests at funerals. But these laws ignore that this form of "protest at a funeral" is not the only possible kind.
Say a person was the victim of a faulty product such as a pharmaceutical and knows they are going to die and the company hasn't been held accountable and they explicitly wrote a will saying they wanted a demonstration against the company to take place at their funeral!
I think this should be allowed. Their wish should be honored and they should be able to go out with a last fight against their assailants.