It doesn't seem like this is really related to a "right to repair". Even if no RtR legislation was passed, it would still be in the military's interest to require user serviceability for everything they purchase. They are a large enough consumer that they could make this requirement and the market would work to accommodate them.
Military-industrial-complex: So, do you wanna buy some widgets?
Lt. Milo Minderbender: well the Army can sure always use more widgets! We’ll need to lock in a contract for spare parts too, so you have to agree to supply spares at a reasonable cost.
MIC: how about instead you take this extended service contract where you pay us to do any necessary repairs?
MM: well that doesn’t seem like a great deal - we’d be on the hook for arbitrary costs forever and you’d have no incentive to make widgets that work.
MIC: we really don’t want to agree to a fixed parts cost schedule. That would annoy our shareholders.
MM: well, we are the US Army, so you can take it or leave it. Who else are you going to sell widgets to?
MIC: ah, but Milo - we can call you Milo, right? - have you considered that you’re coming up on the end of your service?
MM: Not for a few years…
MIC: Sure, but I mean, when you get out… it’d be nice if there was a job at a military widget contractor waiting for you…
Honestly, that sounds like a more benign version of what I picture, which has the military not even giving enough of a shit to ask the questions in the first place.
This would make it a requirement, right now it's not (for all procurements, at least; tech data is expected in large systems acquisitions like a new jet fighter but that's very different than buying a generator). This also brings down the weight of the law, in contrast to a "My commander said so" which can change from one unit to another or even over time.
Or perhaps them not fighting for those clauses is a part of the culture of how the US government - or, more specifically, brass in the Pentagon - deals with defense contractors.
