FTA: "The decision to hold off maintenance for years underscores the unwieldy cost of U.S. 5th-generation fighters, even as the military may be considering a successor to the F-22 and F-35."
Bullshit. Modernization is built into every program, this was/is considered a "YF" aircraft, a Flight Test airframe.
In Flight Test, aircraft are configured in specific ways to accomplish specific types of testing. This aircraft had been configured in such a way and there had been no plans/budget to update the aircraft during its testing phase.
When you're in the middle of production while flight testing and parts/budget are tight, the program is going to let a certain number of YF aircraft fall behind, on purpose.
This is nothing new, the F35s have a couple of aircraft in the same situation and a certain number of YF-117s were as well.