This is the exact thing that your son should research. On the face of it, it doesn’t look like there is much, if any, wiggle room. It also could depend on the intent…future Marine and/or NSW/SEAL screening? MIDN don’t do a whole lot of PT in boots (in the grand scheme of things), so not sure if the running is for strict personal convenience or some other reason. Definitely need steel toed boots for summer training in the Fleet. Lastly, understand that if the chain of command allows one MIDN to do it without really good justification, then it’s hard to say no to others, which then sometimes defeats the point of a regulation. But again, I really recommend your son drive this.