They have demonstrated repeatedly the ability to put the booster where they want it and have the FTS to fall back on if that's not working out for them.
Plus, considering they're catching it where they launched it a few minutes prior when it had 3400 tonnes in the tanks, I think the probability of damage if it did have a RUD on landing with a few 10s of tonnes left is probably already covered in their risk analysis.
Rockets do go boom from time to time, that's why the launch sites are where they are.