The Patriots already sell out every game without Tebow. Merchandise sales are mot at the top of Belichick's priority list and he makes the personnel decisions.
My understanding is that Tebow is being paid league minimum wage. Players earning minimum wage generally don't last long. The Patriots are unlikely to cut Tebow at minimum wage in order to replace him on the roster with someone earning 2x minimum wage but if they do, you would be the first to agree it wasn't an apples-apples swap.
Who at Tebow's salary will better help the team? Tebow takes away some of the negative Hernandez distraction, he boosts television ratings and license sales. For away games, he probably boosts ticket sales and concessions for the opponent.