If you honestly believe that re-using your hotel towels is gonna benefit the environment and you feel guilty for being a baby seal killer otherwise based on your own opinion, then you should follow thru with your ideals, and re-use the towels.
If you’re only feeling guilty because of someone else’s hangups about the environment, well, then I helpfully suggest just getting over it. There will always be someone somewhere who disapproves of something you’re doing.
Or do what I do, and revel in your daily hypocrisies. I mean, look, I’m fluthering when I should be working. C’est la vie!