Ah. Well, my general question still stands: it can't be as simple as just not wanting to be associated, since then she would not have accepted in the first place, so what changed? It's hard to imagine that XiXi's idée fixe, the basilisk, would make her turn it down, and I can't think of any recent scandals like newspaper headlines screaming 'Yudkowsky caught acausally molesting catgirls!' which might do the trick

So my best guess is the other mentioned possibility: she didn't think she could do anything worthwhile with TDT, which is interesting to me since I read a few of her papers and they were pretty good but other people who seem smarter than me and much better at decision theory think TDT is interesting and novel and a good starting point for more work!