TruBelize, I'm Canadian and fly through Houston on my way to Belize. Don't have any trouble with TSA, that is significantly worse or more frustrating than what I experience here or France, Spain, etc.
I will agree, don't want to fly through Miami.
As for making the tourists coming in from Cancun, prisoners on San Pedro, IMO that would hardly be the case. As it is now, flying into BZE immediately puts them into the situation where they are required with time and money to get anywhere else they want to go within Belize.