You are being advised to make a big deal out of nothing. The quick release skewer puts the whole axle into compression. That is one of the main features of a hollow axle compare to a solid one. Tighten the skewer more if you are concerned. Tightening the skewer effectively strengthens the axle. Of course shops don't want to waste their time on nonsense like this. I have no axle problem as far a I know, doing the same thing you are and using the bike for many years. I would expect a bent axle if I got one to come from carrying weight on the rack and hitting sharp bumps in the road, not dropouts causing it.