Maybe OP can ask CX for the identity of that deplane passenger and file a civil claim against him in American court if that guy is an American (just kidding)

Seems most of the problem was caused by that deplane passenger and his luggage. Without the deplane delay maybe no crew change needed and thus less refuel stop time...

My conclusion: US$150 for 30 mins delay by CX is overly generous from my point of view