That's an interesting data sheet. A simple search turns up many such "informational" pages.

Here's one I've found which seems to support the idea that "shock" can detonate nitromethane:

http://www.camd.lsu.edu/msds/n/nitro....htm#Hazardous

Specifically: "Unusual Hazards: Can be explosion hazard, especially when heated. Can react violently with shock, friction or heat."

Certainly, these are ALL possibilities in the average garage. Also, this information refutes your statement that nitromethane only turns to an explosive when sensitized by other chemicals. There's some top fuel drag racers that would also argue that point.

Simply put, the risks involved in mixing your own fuel (Yeah, I know lots of modelers do it and haven't blown up yet) and storing the ingredients are a lot heavier than the price of pre-manufactured glow fuel.

Of course, that's just my opinion.