A barrel roll over the other aircraft isn’t threatening. Stupid and dangerous to be sure. Says he watched “Top Gun” one too many times. Threatening is dropping back into trail, into a firing position. Threatening is lighting them up with fire control radar. This sounds like a stunt pulled by a bored and somewhat overconfident pilot.
I think the Chinese are more disciplined than that and I don’t think it was a case of stupid. I think he probably had orders to harass the surveillance plane.
Au contraire. The barrel roll attack is an effective but not-often used offensive tactic in close-in dogfighting. In the day, I used it successfully many times for a gun “kill” of an adversary Phantom.
TC