I just read how you wrote your ob said you could have tried for a natural if you had not a previous c/s. So he is saying that even if you have CPD, you could have a natural birth except for the fact of the previous c/s!! That is very contradictory. He just sounds anti vbac, nothing to do with the CPD. Obviously he is more concerned with the vbac, not the CPD, which would be telling me that the apparent CPD is not an issue.
And uterine rupture isn't a huge risk either. So you really have nothing to worry about.