Then he wouldn't be in an independent jewish judea, he would be running away from it. Though, I suppose, one of his followers could leave and proselytize in another state. Maybe Baghdad, Persepolis, or Rome.
That is an unrealistic expectation, one that barely exists in both Jewish doctrine and in practical history.
While I agree with you on Christianity being less likely to separate from Judaism on a whole because of it being centered in a jewish country and probably not having Paul, I don't think not having more would be as big of a problem. Georgia and Armenia were the first to convert, so it would be possible to find a patron in the form of smaller states.
But a Christianity without Paul means a Christianity that follows Mosaic Law, which reduces it's appeal somewhat (then again, there are Christian sects that practice it, and there are nations that have converted to Judaism outright). Also, Baghdad didn't exist in Jesus' time. In other news, was there a Persian Jewish community during this time?