Yeah I've tried to get a nut in there and it can be fiddly but a red-yellow Alien (IIRC) slides in like butter.
BrownPants, we don't mean to make you angry. Sounds like you onsighted the thing which is a helluva an onsight. Some of us have been on it one bazillion times. So first off, back up the pin, eh? Secondly, you're exactly in ground fall range when your feet are standing on (next to) the pin. That's where you put gear in again (see above). If you blow the move trying to stand up, you come very, very close to hitting the ground and easily could hit the ground if your belayer were belaying you the way I've seen some belayers belay. So it's not a move to make lightly. It's committing and if you haven't been on the route before, you don't know you can gear once you stand up, and it's not a great stance to fiddle a nut in from. I've personally downclimbed from that spot when I couldn't get something in fast enough. So it's by no means a gimme, but yeah, it can be done safely.