Collective Nouns: I Give Up

From "Lincoln's language and its legacy" by Adam Gopnik, in this week's New Yorker:

"In the past twenty-five years, and particularly since the publication of Garry Wills’s “Lincoln at Gettysburg” (1992), language and its uses has become a central Lincoln subject."

Huh?

Since this is in The New Yorker, I'm assuming it must be grammatically correct.

Perhaps the single predicate nominative (a central Lincoln subject) somehow turns "language and its uses" into a single subject. (I just made that up.)

But it sure looks like a mistake to me.

Here's one from the News Sentinel sports section a year ago: "Most of UT's 2005 signees will not get a full summer of extra work as the vast majority is scheduled to enroll in July as UT's second summer sesson begins."

Surely this sentence is referring to the majority of signees as individuals, which would therefore warrant a plural noun.

After earlier GTOTD's about collective nouns, an assistant headmaster at a prestigious school wrote back: "This issue is perhaps the toughest I face. Appreciate your help, but I still don't get it from these examples, and I've never really gotten it. I've seen a million examples of, 'The orchestra is late for the concert,' vs. 'The orchestra are packing up their instruments,' but I've never had a really satisfactory answer."