she is rather enormous, and i agree looks like a pk male. Look for the ovipositer right behind the ventrals, looks like a little white dot thats kind of sticking out. If your betta has it its a female.
It does have a creamy white body so it would be a bit harder to see. Also its fins are too long to be a PK my 2 have really short fins. in that picture "her" fins droop down. im guessing its a very old female vt. unless he can not find a little oviposter