Ability to "lock" sulfur cubes to prevent direct block replacement

I believe the ability to swap blocks in sulfur cubes will limit the variety of minigames you can create with them. Let's say I want to create a soccer variant where you can build with blocks to defend your goal or interfere with an opponent. In this scenario players will be able to change the properties and appearance of the sulfur cube using their building blocks, which is something I don't want them to do.

I understand that some creators might find this behavior useful for their mini games though. So I propose adding a way to "lock" the sulfur cube somehow to prevent direct block replacement. The first idea that came to my mind was using a honeycomb on a sulfur cube as a "locking" item.

It would still be possible to remove a block from a "locked" sulfur cube using shears. If you split the "locked" sulfur cube, the small cubes wouldn't be "locked".