It was actually a lot of reasons that finally made Melhed join the fight. Not wanting to be painted into a corner of the map forever behind friendly realms, not wanting to stab an ally and suffering from Too Much Peace is probably what swayed the majority of the Senate. Opportunism was hardly a factor at all.
The decision took ages even by Melhed standards. Both Fronen and Thalmarkin had close friends in Melhed and the debate was particalurly infected with votings made over and over due to technicalities.
