One positive for sure is the fact that both parents came to the interview and that it isn't goign to be an arrangement with one parent only. I had a set of parents separate while in care and it went well. To this day they act like a married couple in terms of care/school events, etc. for the child.
Another set of parents came just like the ones you have now and I made them both sign the contracts as it says "parents of" on my forms. It meant both had agreed to all of my terms etc. and on the can pick up form were names from both sides and both parents had signed the form. Yes I had to be flexible knowing at any point there could be switches in which parent was picking up etc but in truth that happened less often than with my married parents because there were distinct rules about who had child what week. On the flip side just as we often do with a single parent is be a little bit more lenient with slightly late pickup etc. knowing there is no other parent to come instead.
If you do take them I would be very honest with them about potential concerns that could come up and let them know how you intend to handle them with the answer being immediate dismissal with no notice if behaviour and conflict becomes detrimental.