I've never been able to select a seat in PE (PV) in the bulkhead when I've purchased tickets. Sure, could be already sold out. But our last flight had many open seats in PV and I still wasn't able to select a bulkhead ahead of time (there were some that flew empty, even in the bulkhead). Now, I don't actually like sitting in a bulkhead, so I've never tried to get those seats at check-in, but I can see how that could be a restricted row for disabled and/or infants in bassinets?