Honestly I don't think it should be against the law or anything. There could just happen to be a protest near a funeral site. But I would consider it quite rude and disrespectful. Though they may have not known that there was to be a funeral that day I think if it was no huge problem it might be considerate to reschedule.
Say there is a business meeting between two notorious corrupt institutions going on a block away. The protesters are shouting and directing their complaints towards the business meeting not the funeral. Yet under laws targeting protests at funerals they usually do not specify that the protests to be banned are ones targeting the funeral.
That stipulation should be put into the law. Protests that aren't targeting the funeral should be left untouched.