It's stable when pure. This guy made his own, and lost three fingers in the process. It seems to have developed a reputation with suicide bombers, probably due to the illusion of easy manufacture.
The articles I’ve seen do not imply he lost his fingers working with it.
I’ve also never seen it associated with suicide bombers, you may be thinking of acetone peroxide chemistries (e.g. TATP), which are common low-grade explosives used by terrorists. Also highly inadvisable, TATP is a pretty shit explosive in almost all aspects (low power, low stability). Someone stupid enough to be using TATP should not be using HMTD, as the latter requires more discipline than TATP.
There is a technical gap between making HMTD and processing it into a form that can actually be used in practical explosive systems.
