Science is explicitly NOT a moral pursuit. Science is objective, morality is subjective. There would be no need for morality if things could be scientifically proven good or bad in the way that things can be proven true or false, or arguments valid or invalid.
Science does seek truth, morality does not. The best it can seek is consensus.Science is indeed impartial, morality is about picking a side. "Collective well being" may be one end goal of scientific thinking, but never at the expense of truth, and as soon as one engages in science specifically for such a goal one is no longer impartial.
Also date-rate is a poor topic for such an experiment as it is easy for most people to conclude that it is wrong based on universally shared principles (note: nothing to do with science). In fact it sounds like the researchers didn't even think twice about forming such a moral position in advance and merely compared to which degree the participants chose a moral position that agreed with theirs. Far better would be the trickier issues like political positions, abortion, polygamy, homosexuality, vegetarianism etc.
Even if the experiment was sound, the interpretation is ridiculous. The observed correlation could still be interesting, but we would need to conduct more, better, experiments and interpret the results better.
My hypothesis would be : Assuming science enthusiasts go on less dates as young singles than the general population they have less exposure to situations where tricky situations arrive, i.e. getting drunk and having sex. Many of the less-scientifically minded have probably had situations where a mistake was made, or judgement was poorly executed, and are less likely to make blanket judgements condemning certain behaviours outright. A science enthusiast that hasn't been in that situation is likely to consider himself, should he find himself in that situation, as being capable of exemplary behaviour, he may not consider himself as likely to make mistakes, have less tolerance for mistake making in general, and more prepared to take a harder moral position against the very human behaviour of making mistakes.
And what the hell is "belief in science"?
I have seen more intellectual rigour on /r/Atheism