It is possible that one person in that hall already had doubts about 1914. Hearing someone else (even if not in the "proper" way) express doubts about that may help such a perso
I doubt that. When someone is this rude and childish nobody takes them seriously, they just think the Watchtower is right when they say apostates are evil and mentally diseased. Jehovah's Witnesses have a right to worship in peace as does every religion. These people could be arrested for trespassing. I fail to see how that is going to wake anyone up.
When I was still a JW I once saw a woman standing in the median of the street, dressed all in black, including a hood covering her face. She was jumping up and down and waving a sign that said something about what Jehovah's Witnesses had done to her. I know now that the elders are capable of great cruelty and she had probably been pushed over the edge, but at the time I just thought she was a loon. It wouldn't have caused me to question anything, quite the contrary. Men trying to disrupt the memorial would not have caused me to question either, most JWs will just think Satan is trying to make things difficult for them, if anything it reaffirms their faith.
There is a place for activism, if you think it will do any good, but the kingdom hall is not that place. In my experience people will leave when their own experiences or reasoning cause them to start to question things. Until then there is very little anyone can do to wake them up.