Completely and totally incorrect...I can name off about 20 different species that would work perfectly with mollies. Please don't make broad generalizations about a family of fish as diverse as cichlidae. While many rift lake cichlids are aggressive, there are also several calm species in those lakes, as well as west african riverine species that are quite docile, as well as many south american species that are more peaceful than the mollies themselves. There's even central american species that are peaceful, and most of the highly aggressive species come from central america (festae, beanii, etc.). Don't take this as an attack, but ratherlearn from it. I love the peaceful species of cichlids and hate the generalizations that are bad that they are all either huge or aggressive. A perfect example is my avatar, a Uaru amphiacanthoides, a 10" or so cichlid from south america. She lives with inch long cories, lemon tetras, rummy nose, a absolute baby german blue ram (another peaceful cichlid), etc etc.
With that being said, mollies do not belong in a 5 or a 10 gallon, and although there are cichlid species that could live in tanks of that size, i wouldnt do it, as there is no way the bacteria in the filter could handle the bioload of 5 adult mollies, plus other inhabitants. My advice is go buy a 20 long, it'll be better for the fish, and you can do much more with it.