I can't speak to Babygravy9 mind or character, but if "being pleasant" is in any way related to intellect, Isaac Newton must have been a simpleton - he was a famously unpleasant and vindictive person.
We know that Isaac Newton wasn't a simpleton because he wrote the Principia. I think you will search in vain for any output of similar intellectual quality by this particular individual.
Ok. I guess it doesn't damage the credibility of this conference that they've invited an anonymous racist troll as one of their speakers because no-one is as smart as Isaac Newton.
I am not in the US. I have decided for myself on the basis that (i) the first word of the tweet I linked is a nasty ethnic slur and (ii) its contents are merely schadenfreude over someone's raw emotional outburst in response to a traumatic event. There cannot be a good reason to invite such a person to a conference except to send a clear signal about what kind of person is welcome there. I think you know all this, which is why you respond in such an oblique manner.
I'm pretty sure all kinds of people are welcome there.
I don't approve of the guy's tweet, but I also do not limit myself to groups of people that share the same views as me. Take the good, ignore the bad. There are some remarkable people there.
Credible on what grounds? It's just another facet of the ignorance around the subject, no one has a good answer to what's happening and this Natalism movement is not it either.
I'm sure this group of mostly far-right weirdos are definitely NOT going to approach the question of "Why don't women want to have more kids?" and end up with something that resembles the Handmaid's Tale. Absolutely not.
The only credible approach to this is issue can be found in this corner of the discourse: https://www.natalism.org/