I'm still an amateur when it comes to pit husbandry but I've had a male 5 ft black pine now for about 3 years and I've learned n to not worry too much about his appetite. He's always been very picky, I often house him with a 5 1/2 female, so temps are not the problem...she hardly ever refuses a meal once she's defecated the last one. I have a male cape gopher too, he's worse, goes off feed entirely for 4 or 5 months during the breeding season accepting only a few pinkies here and there.
My male black pine seldom refuses baby chicks but I find it hard to procure them on a regular basis and they're not recommended as a steady diet. He's eaten fuzzy/pinkie rats pretty consistently this year but I offered him a live medium sized rat out of desperation about a year ago and he killed it but just like yours couldn't seem to swallow it. Yesterday, I offered him two medium fresh killed rats and he chomped them right down. Go figure....I've learned not to worry unless they are losing a great deal of weight (pits get a gaunt triangular look to their spine when they are truly underfed, learned that from a rescue) Keep him the right temp, try chick if you have them and don't worry much about it...good luck, love those black pines...I have a baby from last year about 37" now...decter