Recall that a similar set of actions (by Senator Reid , et al) previously. In the 110th Congress, a number of bills were introduced to close lands which were not able to wend through the process and be approved. In the opening days of the 111th, an "omnibus" land bill was introduced and pushed through with a minimum of discussion. It was much easier to pass a large conglomeration in one bill. It certainly bears watching for another attempt this round.
Apparently, a legislator is less likely to question the inclusion of the other 98% of the land involved as long as their pet project is included. In correspondence with one of my Senators, her response to the thousands of acres of land included was essentially that she didn't care as long as the 20 acres she cared about in our state was included.