That part of the testimony was finally unredacted in the Epstein files that were released to the public recently, it turns out the scientist in question was Stephen Kosslyn, not Steven Pinker. You can see for yourself:
https://ep-nov-12-data.greg.technology/006/HOUSE_OVERSIGHT_021174.jpg
I searched the files for both Yudkowsky and Pinker, Epstein seems to have known who they were but there aren't any emails or direct correspondence between them and nothing incriminating (yet)