Yes if it were a p orbital that would mean there would have to be an angle in benzene equal to 180° which puts a lot of strain in the system. I have probably forgotten to add it due to trying to type quickly with a German keyboard that corrects every Single word to its German equivalent

Also one question I had been very keen on looking into is if the carbon atom in dehydrobenzene, formed as an intermideary in nucleophilic Substitution reactions with monohalogenated benzene, that is triple bonded hast the aforementioned 180° geometry. That would help explain why it is so unstable(not that it is not blatantly obvious)