If you rehome the Mollie then you can afford to have a small shoal of some micro fish - Ember Tetras or Green Neons etc.
I don't mean to put people's advice down but a lot of people on this forum can be very ott about
OVERSTOCKED!!!!.

60l really isn't THAT small. You'll be fine with a small shoal. I have a 60L and look at the fish in my sig. Granted yes I am a bit overstocked but there's a huge gap between what I have and what you have...if you see what I mean
I understand your point, but unless the person is prepared to do the quantity of water changes with a "overstocked" tank, it is a bad idea. When I was a kid my dad would pack the tank with a ton of fish, and we would all love it. But, then the fish would slowly die off for a while, until it was no longer "overstocked". Then the survivors would enjoy a very nice life. If we had known that we were actually overstocking the tank, we would have either 1) gotten less fish, or 2) performed more maintenance to ensure better health for all of them. But, 25 years ago there was far less information at your fingertips about fishkeeping. It pretty much came down to what you heard at the LFS, and we all know how that can vary. We just assumed that fish were extremely delicate and half the stock would die off in a month or two before you would be able to figure out who the strong ones were and they would be the ones who would remain in the tank for a while. Then we would get more and the cycle continued. We didn't know any better and no one told us.
I'd rather warn folks and teach them the proper way to deal with the problem.