My thought was similar, at least to the latter. Hospitality is important to these vampires. Prestige. To be forbidden to see and be seen means losing advantage and opportunity.

[She hums a little, considering.]

Yet if the punishment is too harsh, then he will have to expend his own resources to monitor the vampire for compliance with it. It would be a gamble, I think. He would reap great benefit from the example, if it were successful. But if the vampire were to circumvent his punishment, he would appear unable to enforce his commands.