The main explosive in the Oklahoma City bombing was probably C4, that fertilizer truck was just for show. But this is off-topic!
ANYWAY!
Yes, nitromethane is sensitized by bases. But as I said before, this reaction is done in a solvent. Also, it's acidic, and when you finally basify it there shouldn't be any nitromethane left.
If anyone manages to detonate a diluted solution of nitromethane then better file a patent for it, because you have achieved what many before you tried but nobody was able to make it work.
There won't be an explosion. It's impossible for this mixture to detonate.
I'm not fat just horizontally disproportionate.