Off-screen randomization

I was in a stream with a breaker who claimed he did all randomization off screen after the stream ended. This includes all entries into giveaways, including buyers giveaways. The lobby pressed him to do the randomization live before he ended the stream for a fairly valuable buyer giveaway, but he was not happy with it. Is it permissible to do things like buyer's giveaways off-screen so that there is no record of who actually won it? This guy seemed intent on the giveaway going to a specific person, which I think was why the lobby really wanted him to do it live. Just trying to figure out the specific policy, if there is one, on WN.