How explicit was it? Couldn't they have just toned it down to fir the final version of the movie?
I have a feeling it was mostly cut for pacing. Like, she zips down her top a bit, but that probably wasn't an issue, since she never zips it back up for the for rest of the movie (the continuity error mentioned earlier in the thread). The aliens are a bit frank about talking about how attractive they (don't) find her, with one comparing it to beastiality and the other one being kind of into that but, again, that's not much more risque than the alien make-out scene in the same part of the film. On the other hand, I've seen "This Film Is Not Yet Rated," so I know it's not unthinkable the MPAA thought America's children would be driven mad with lust by seeing Sigourney Weaver actually in the act of putting a bit more cleavage on display, but not by having said cleavage inexplicably appear unannounced for the last fifteen minutes of the movie.
Watching the deleted scene on the DVD, and considering how the sequence plays in the finished film, it just stops a fairly propulsive ticking-clock sequence dead in its tracks, and blunted the whole "The countdown can't stop until '1'" gag since they'd spent two minutes on a very cheesy scene.
But don't take my word for it, the deleted scenes are on Youtube.
I think the article exaggerates the situation a bit, probably from a combination of how long it's been and Weaver making it a better story in the telling, and the writer doing the same for the clicks. Given the script linked above (which is actually missing the aforementioned "Oh, that's not right!" romance subplot entirely) and the deleted scenes, my guess is the director was going for PG-13 (one solitary "fuck," a few "shits" here and there, no actual nudity or gore), caught the ratings board on a bad day (maybe they thought "Fuck that!" counted as using it as a verb), and since there was so little objectionable in the movie to start with, the cleaned-up edit brought it all the way back down to PG.