According to their current band plan for 50 to 51 MHz:
50.0-50.1 CW, beacons
50.060-50.080 beacon subband
50.1-50.3 SSB, CW
50.10-50.125 DX window
50.125 SSB calling
50.3-50.6 All modes
50.6-50.8 Nonvoice communications
50.62 Digital (packet) calling
50.8-51.0 Radio remote control (20-kHz channels)
It would seem to me, it a station was using this HSMM with a 200 KHz bandwidth (+/- 100 KHz), the closest center frequency they could use is 50.4 MHz. Anthing less than that violates their current band plan. If this HSMM can run at something less than 200 KHz bandwidth, then they can creep closer to 50.3 MHz but not go below it or it will "violate" the current published band plan. But, but, didn't we read somewhere that all band plans are under review by some unnamed task force in anticipation of the "proposed coming of the FCC's new deal".