Really? I've never actually looked into it. I feel like they're a P bass + because they have the precision pickup.. and then the jazz as well. Couldn't you just roll off the jazz pickup and basically have a P bass? But even so, there was no denying that Fender PJ sounded incredible. Perhaps it did not sound like either a P or a Jazz, and it simply sounded like an individual PJ. A category of tone to its own
Bongolation is a P bass purist. If you are too then you should listen to him. Otherwise it is safe to ignore him or wait until he develops a more nuanced stance to listen to him. P/J basses are made in a variety of forms. Out of the box a few do an excellent P bass impression, most do not. Many could be modified to do an excellent P bass impression, probably most cannot. But you are doing what you should be doing when you buy a bass: you are listening to its tone and deciding that you like it. What more could you want?
The P/J bass is evidently quite popular. Take a good look at the Fender lineup and you will see that there are many of them. A lot of other people make them too. If you want a P/J that can sound like a P bass then you need one that puts the P pickup in the right spot. A few do but most do not so they can never get the P bass sound exactly. Most Fender Jazz and Jaguar bodied P/J basses have it slightly off. Most Fender (but not necessarily other brand) P bodied basses have it in the right spot. The Fender Reggie Hamilton, my favorite bass, has it very, very close to the right spot and it uses an actual P bass pickup. The pickup loading is a bit off because of the blend pot but on the whole it cops an excellent P bass tone. Reggie Hamilton uses it in P bass mode for recording work so evidently a lot of producers (who are noted P bass tone fanatics) agree that it can cop a P bass tone. Of course if you were to assemble 20 actual P basses from over the years and compare them to each other you would find a lot of differences in tone. Which P bass is it that the P bass purists want to sound like, eh???
In terms of sounding like a Jazz, well, you would need two Jazz pickups to do that and again which J bass is it that you want to sound like? Fender has used at least two different pickup spacings on their Jazz basses and who knows what the copycats use? So yeah, it is best to think of the P/J as its own beast, keeping in mind that if it is done right or modified suitably it can cop the "P bass sound". Whatever that is....

