Ideally, an audience would pick up on the bad-faith side not addressing arguments, engaging in personal attacks, making unjustified claims, etc. and be unimpressed. The interrupting especially should prompt some intervention by a moderator, but usually they don’t have a means of preventing it from happening other than chastising after the fact so it still relies on some degree of human decency.

I’d still call it a debate, just a poor quality one.