Description of feature
Describe what you want in the mod. Make sure this was not already suggested. List of commonly suggested features: #217

my idea is to make the command block that spawns the wither storm a new “survival mode” command block. The only difference between it and the normal command block is that this new command block can be broken with a command block tool, and also can be placed in survival. The gui can still only be used by opped players in creative mode however.

If this were added, I think the wither storm in phases 0-3 would drop this new command block as well as a nether star.

This mod does effectively what you're looking for with the only downside of the block not dropping after breaking it. I don't plan on modifying command block properties myself.