A lot of inference going on here. Just to reiterate, my dad hasn't mentioned his talk to me; the invite came from my sister and I don't believe she's asking on behalf of my dad, they don't live together. If my dad wanted me there he would ask me himself. It may be my dad's first public talk at a kingdom hall but it isn't his first public speaking gig, he used to work in sales.
If my dad were to invite me personally then it would be different, although I still don't think I would go, for the reasons I've already stated. I detest the Watchtower and everything it stands for; I'm an apostate, an atheist, and by Watchtower standards an immense sinner. If I were to invite my dad to watch me give a talk on evolution, he would not come, and I would not expect him to. Likewise, I'm not setting foot in a kingdom hall if I don't have to, they make my skin crawl.
Going to a wedding or funeral at a kingdom hall isn't going to give anyone false hope as these occasions are not about the organisation. Public talks however are about the organisation. Those who are telling me I should go are making a lot of assumptions about the situation based on limited knowledge of it. I never for a minute implied that I was considering going or wanted convincing; all I asked for was advice on how to diplomatically decline the invitation. It should have been evident that I have many reasons for not wanting to go, some of which I think it's pretty clear are too personal for me to share. No big deal indeed...