that surely can't be the reason to refuse a RMA. If Asus believe these screws should be tightened to secure the motherboard, but not overtightened to prevent damage, then where's the torque settings, if it's that vital?!? The x470 strix manual (one at hand) only says "place nine (9) screws into the holes indicated by circles to secure the motherboard to the chassis" and "Do not over tighten the screws! doing so can damage the motherboard". Other instructions for different items have torque settings to prevent overtightening, so it's a little off for Asus to claim it's critical to tighten the screws securely, but not too much, without any indication what too much is. My road and mountain bikes have torque values for all their screws listed in the manuals, so does my car for everything from wheel nuts to most of the service manual.
Yes, I know ppl will laugh at this comment, as why would anyone have a torque-driver for building a pc, and I agree. But, if a company want to fall back on a statement in their manual that it should be secure, but not over tight, then they need to back up their statement with values/metric.