http://www.msc.navy.mil/annualreport/2001/pm2.htm
Ocean Surveillance Seven government-owned ships and one chartered vessel supported the Navy's undersea surveillance needs in FY 2001. USNS Prevail, USNS Assertive, USNS Bold, USNS Loyal, USNS Victorious, USNS Able, USNS Effective and MV Cory Chouest worked directly with units from the Navy’s numbered fleets. MV Cory Chouest, a privately owned and MSC-chartered ship, also continued to test a new sonar system. This new system will be installed on a new MSC surveillance vessel, USNS Impeccable, to provide both active and passive sonar capabilities. Impeccable was under construction as of Sept. 30, 2001.
It's a spy ship, not a minesweeper, and that's according to the USN.
You said — “It’s a spy ship, not a minesweeper, and that’s according to the USN.”
Well, I think it was a minesweeper by “design” (as it was originally made and thus an apt description), but it was engaged in intelligence gathering operations, dragging a sonar unit designed to track Chinese submarines....
So, you could say that either term fits what was happening. It’s a proper description to say it was a minesweeper and also, the article does make it clear that it was engaging in intelligence gathering operations.