I agree with those who say this doesn't feel like an epic monster. I've been trying to articulate what I think an epic monster should feel like.
I don't think epic monsters all need heaps of special abilities. Dumb brute monsters still have a place at epic levels, and you still need mook fights for contrast and a change of pace--not every battle can be a boss fight. But...
Epic threats should feel rare and special--not in the sense that you seldom fight them at epic levels, but in the sense that they occupy a position at or near the top of the game world's power spectrum. The presence of an epic monster, even a mook, should have a dramatic effect on its surroundings. A malebranche (or war devil if you prefer) may be a mook in Epic-level terms, but it's still a GIANT FREAKING DEVIL that could lay waste to a castle or a town all by itself. You don't get a gang of malebranche showing up to attack you unless you've personally pissed off one of the Dukes of Hell. If you see malebranche just kind of hanging out around some minor evil temple, it destroys any sense of perspective and ruins the feeling of "epicness."
An epic-level monster, if it's awake and active, should make its presence felt for miles around. And I just don't have that sense from swordwings. It's a fluff thing more than a crunch thing (cue cries of "You can just change the fluff!" from the peanut gallery, to which I reply, "You can just change the rules, too, but that doesn't mean bad rules aren't bad").
A swordwing nest by rights ought to be a thing of terror in the Underdark, a place where even drow and mind flayers fear to tread. Any nearby community, even a drow city, would fear the arrival of a swordwing "collector." Lesser races like troglodytes and kuo-toa might worship them as gods and offer up sacrifices in hope of appeasing them. Instead, the description makes it sound like swordwings are just another random Underdark oddity that PCs stumble across from time to time.
Now, to be fair, this may not be the entire Monster Manual entry. I hope the full page spread suggests a bit more in the way of how they affect the lands around them. But from the description given here, this is a Heroic-tier monster on steroids, not an Epic creature.