Mz trainer tried this with a dressage whip and I walked out of the training... Probably not the polite thing to do or the best idea. Just tell your trainer about how you feel and be clear about it.
It's not a good idea... maybe your horse will get comfortable by someone chasing him to jump so when he has to jump by his own he will feel his not forced to do it and probably don't jump... just tell him it's not a good idea to force him like this to prevent future issues
Tell him that your not comfortable with him doing it and maybe ask him can you use your own whip on your horse and then only use it if you need it