Not quite.
Rivals' marketing campaign made a sizeable deal out of "look! Ferraris! Cops! Cops in Ferraris!! And even somewhat in the way you think it is!!!", so they were definitely chaseable there. As they were in 2015. Well, I say "chaseable in 2015"..
Aside from the first game (which I haven't had a chance to try myself and Google is being awful right now), I believe the only times they've been blocked will have been in 3:HP (and even then you could use one of them in the PS1 version) and HS. In other words, they've been chaseable in more games than not. Besides, considering what gameplay is like these days, it would be extraordinarily awkward if cops weren't allowed to chase specific cars. Could be a decent little easter egg if they didn't chase Testarossas, but that's about it.
Also I guess I'll sign myself up for the waiting list for a GTP crew on PS4. Not only is FOMO a 🤬 but for once it feels mostly justified.