It's not everyone's opinion, but most of my Malawi tanks have mbuna and haps/peacocks in them. You just need to have a feel for aggression.
It all depends on which mbuna you put with the venustus.
Put in a small one and they'll end up an adult venustus' lunch (saulosi, demasoni, afra)
Put in a larger, more aggressive one and they'll terrorize the hap (crabro, elongatus tropheops, larger zebras)
They'd be fine with middle-of-the-road mbuna imo. Something like red zebras, acei or yellow labs would be perfect, so long as they aren't so small to start out to be lunch.