It's up to you. I'd probably try to avoid disinfecting my live rock if it was possible. Maybe try the steel brush with fresh water, to remove the Neomeris without killing everything else. The problem with killing all life on the rock, is that you are left with a blank canvas for new algae to colonize, which may be worse than the neomeris.
I don't know if hydrogen peroxide is a better choice or not, but I know some people use it.
When I broke down my tank about a year ago, I had aiptasias everywhere, dinoflagellates, and some 'pest' macro algae. I drained the tank and disinfected it using bleach. I also disinfected my small amount of live rock, making it dead rock. So I bought more live rock for the rebuild.
If you are ready to break down your tank to fix the issue, then peroxide or bleach makes sense. If not, my suggestion would be to try to remove it without killing the rock. It's not a fast growing macro, according the guide I linked to, so a very thorough manual removal may well do the trick, with occasional, say monthly upkeep.
Honestly, I doubt I'm the best person to advise you, so it would be helpful for others to chime in. Any suggestions? Bleach v peroxide? Replace the rock? Lots of options, but I don't know enough specifics about your situation to make a strong suggestion.
Tank size? Number of rocks? Are corals encrusted onto the rocks? If not, you could leave your corals in the tank, and put your rocks in a trash can with the top on to give them a week long black out. Lots of options. Use the search here on RC to find out what others have done in your situation.
Good luck!