They're credible enough. I'd like the sample sizes to be bigger as well but they're enough to verify that even if the bot got lucky over the sample size, it's close enough that it doesn't really matter. Add a bit more compute, optimize some algorithms a little, and you'd make up the difference. The real point is that they have a technique that scales to 6-max, and whether it's 97% or 99% is kind of immaterial in the grand scheme of things.
FWIW, they did some variance reduction techniques that dramatically reduce the number of hands needed to be confident in your results, so the number of hands may be bigger than you think. e.g. the results of 10k HU hands have much higher variance than the results of 10k HU hands where everyone just collects their EV once they're all in.
FWIW, they did some variance reduction techniques that dramatically reduce the number of hands needed to be confident in your results, so the number of hands may be bigger than you think. e.g. the results of 10k HU hands have much higher variance than the results of 10k HU hands where everyone just collects their EV once they're all in.