In the research paper I found on the Comanche controls, it said the altimeter switches over to Barometric Altitude at about that height. It wasn't supposed to stop dead. It would be reasonable though, to simply extend it up to 1500 ft (or more) like the Apache. The Russian Helo altimeters switch over at 300 meters.
https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19940008849.pdf On page 424 it says the altimeter switches between radar altitude and barometric altitude at 300 ft. The HMD shown in the paper is also reversed to the EECH HMD, the altitude is on the left vs. the right on page 425. It could have changed when they built the prototypes, though.
I also just read a description of the Ka-50 Blackshark control modes. It's just as capable as the Comanche, but far more complicated to operate than ours.