Hmm.. I recalled I still have some half-dead Harvester, and I tried putting it to work while all other items are still under repair.

And it worked. It feels wrong.. If the no-starting-a-repair-while-mining-is-active was meant to extend the "reuse cycle" and require a "truly dead time" after a mining session, then allowing it in the other direction feels like easy exploitable with even just two sets of items to swap A/B, mine with one set while second set is being repaired, and this makes the original restriction feel useless..