The existing towers can only handle empty ships & boosters. The tower stacks them, then they’re fueled. A catch-only tower would avoid some cladding and the propellant loading lines, but it would still need a deluge system and a QD arm to replace any remaining propellant with inert gas. At that point you might as well pay a little more and get a fully capable tower.

landing footage shows exactly why they didn't attempt the tower catch - the final braking burn was engine rich (green tint), it didn't blow up, but there was a respectable chance of it just crashing into the tower running on less than fumes

The goal, as I understand it, is to return the booster with as little fuel as possible at time of catch -- and not run short.

The booster footage indicated to me that its engines turned off, and then the body of the booster imploded, before it touched the ground and then became the expected fireball.

I'm definitely not a rocket scientist, but this series of events leads me to believe that the fuel was absolutely exhausted.

Their risk tolerance would probably be greater if both towers were fully operational. But any damage to the only functional tower during booster catch = an automatic abort to the ship catch one day later, and the ship catch is what was really interesting at this point of development.