As with other people in the comments section, I also don't think this is going to end well and the MC is thinking too shortsightedly on this answer.
If this was the first prince or princess or someone of high authority within the Jenerett Kingdom, maybe this capture method would work, but the third prince means piss all in terms of actual meaning, and now that the Beastman Kingdom has him, the Jenerett Kingdom has an excuse to go full on war and capture/enslave everyone in their path, third prince's life be damned.
If this is all part of his plan, this plan better have more steps to this because this is not an answer, this is like a bandage covering a crack in the wall.