They would have to be really really REALLY fucking stupid to try and pull anything off at a con. Riley stalking Eric’s business at night/during the day and fucking with his ancestor’s grave were stupid as hell, but it was a mainly secluded area with little to no people around. To do anything at MEGACON would be in front of hundreds of witnesses where any number of things could happen that result in Riley getting his ass handed to him by SOMEONE, and the police would definitely get involved. And once they see “oh, this guy was previously stalking this man’s business”, and it would just heavily snowball from there.