Yeah, it just seems... odd, really. You'd think that the men near enough to engage the one enemy guy who has gotten in among the unit would switch to swords to dispatch him (leaving those out of sword range still to poke others/him), then go back to poking if possible. So then it seems a bit far fetched to have that one enemy guy trigger pretty much everyone busting out swords and keeping them out for the duration of the fight. We all sorta agreed that pikes are supposed to poke poke poke all day long, so at the very least their vanilla behavior is extremely undesirable, even if not a bug. Take into account that they have at least one other bug (one where when ordered to attack they simply march through the enemy unit, never lowering the pikes to try to attack) and it seems even more likely that the sword thing is not their intended behavior either.