Well I don’t personally want to chance that the Met police have a special “they’re a demon not a gorilla” clause written into what they can taser and ship off to DARPA/Porton Down or whoever, when I decide to go on a 12-foot tall muscle-bulging horned demonic rampage down the high streets of Britain… 
It’s like flying and other flashy siddhis, why draw attention of a kind that will almost certainly bring more problems than gains, simply to be ale to say you did it? I don’t need that level of proof since my “evidence files” are already jam-packed with things that blew my mind. JMO though! 