I don't think it's the IPO per se that's the issue. It's that IF something giant is in the pipeline, the owners of GF would surely reveal it before the IPO is priced (i.e. in the next couple of days) because you'd then be taking in hundreds of millions extra. Literally hundreds of millions of pure profit just for timing the announcements together.
If they don't announce anything, either there's no collaboration or, more likely, it's a little premature to announce.