Personally I didn't find that guy very convincing. I think current frontier AI would already probably enable a non-expert to do gain-of-function work on a virus which could result in something like Covid.
And AI looks to keep getting better, and if it does then I don't see why it wouldn't become superhuman in virus design too.
So I'm going to assume that the p doom for bioweapons is 0 in terms of existential threat (pandemics kill millions but not everyone).