I've not, thought I'm somewhat familiar with Massimo through his other work. Would you recommend it?

No I haven't nor is it high on my priority list; for that matter, I know little of Stoicism itself aside from a few aphorisms and axioms -- the di/tri-chotomy of control, the Four Virtues, etc. As for why, I have the unfounded belief that Stoicism alone is too pacifistic thus is ill-equipped to handle malevolence at an interpersonal and societal level. I would need to read and research to get some answers though.

In the case of training a fighting force, doctrine of the enemy is often as beneficial to study. That does not mean stoicism is being promoted as the doctrine of either side, however.

Obviously stoicism makes a useful tool for someone who must endure the incredible hardship of soul that special operations must endure, however it's important to note that it is equally useful for the enemy to be just as resilient.

It wouldn’t surprise me if Spetsnaz also studied it, it would if ISIS did

I read it, it was interesting but if you are looking for actionable advice I'd go for the William Irvine book first.