My male betta is pretty friendly. I can put him in my ten gallon with the other fish and he minds his own buisness. I also kept a female guppy with him in his bowl for an afternoon while I waited to get my one gallon.
But usually you shouldnt keep male bettas with any other fish. If your betta flares his gills at you and other fish,then definitely keep him away from the guppies. My betta doesnt flare his gills ever, he just gets nervous and swims away. The betta will nip at your guppies tails anyways.
I had a male VT betta in with my guppies(male and female) and they got along fine, VT's usually are more calm than any other betta, but the decision is up to you, you can try and just watch him, if you see him attacking or nipped fins then take him out