Their launch license requires them to initially aim at the water, and only shift to aiming at their tower if both the booster internally judges it's in perfect health, and they send the signal from their control system.

I think there is a reasonable possibility that something goes wrong enough at some point for the booster to go in the drink. But if that happens, maybe it'll be close enough to the shore that we'll get some nice video of it?

This is also standard procedure for Falcon 9 landings. They would do it this way even if the launch license didn't require it, because they know the probability of some sort of failure of the booster is high, and they don't want to destroy the launch tower if they can help it.

At the moment of landing burn ignition the booster will already target the beach near the tower.

Elon has pissed me off beyond all reason these last few years but when he says “excitement guaranteed”, it’s the truth.