FWIW, I am a physical chemist -- and I fear that you are under-informed: As you, yourself, noted in your final statement, nitromethane (properly catalyzed and/or highly shocked) is capable of detonation. In other workds, it is a high explosive.
For your enlightenment, I offer the following on-line technical papers as references:
http://www.cyberhost3.com/nitronic/research8/shelly.html
A great part of the considerable interest devoted to nitromethane, the simplest explosive nitro compound, is related to the understanding of the chemical mechanism of initiation of detonation. Experimental observations show that a careful study of the methyl group, in particular that of the highly excited [[nu]](CH) vibrational states, could bring some information to elucidate the initial chemical mechanism of decomposition, including the means by which intramolecular energy transfer processes can occur. Actually, one interesting peculiarity of the methyl group in nitromethane is the low value of the potential barrier to internal rotation, which is essentially free at normal temperature. Its coupling with the other vibrations, especially with the CH stretching modes, could affect the vibrational energy redistribution and thus the nitromethane reactivity.
and...
http://www.aps.org/BAPSSHOCK97/abs/S1700.html#SG1.005
Session G1 - Nitromethane.
MIXED session, Tuesday morning, July 29 CCA,
[G1.01] Mechanism of Chemical Decomposition in a Shocked Condensed Explosive
Based on these P-T Hugoniot data, we construct the detonation diagram of nitromethane, which consists of no-detonation, super-detonation, normal-detonation zones. In the super-detonation zone between 12 and 19 GPa, the shock-compressed nitromethane detonates with a significant induction time; whereas, the detonation occurs nearly instaneously in the normal-detonation zone above 19 GPa.