The problem with Jason is that he does have an injury, and he really can't train at full strength in the 5.5 weeks leading up to Worlds. He clearly ran out of gas in his FS because the limited training time affected his stamina. That is likely to be the case at Worlds as well, and unlikely that he will be able to include a quad in his FS at Worlds.
I'd have no problem with Jason at 90% of competition readiness. But the Jason at 4CC was only at 80%, and I'm not sure that he can improve that by 10% given the time and limited training.
Then the question becomes: Who is a safer pick for Top 10 at Worlds, Jason or Vincent?
That's the person who should be going to Worlds with Nathan.