Far as I remember, the decision to take on 1630 and to later drop 970 was made by Granum Communications in 1989. Seems like the FCC's 'AM Dial Expansion Act of 1989' specified that stations could apply and receive a frequency in the expanded band (1610-1700) BUT they would have to surrender a station that was in the old band, and I believe the surrendered station had to be within an overloaded part of the AM dial, or (like 970) could broadcast daytime-only...and would get to broadcast 24 hours a day at the new dial position if they made the trade.
There was a specified time this turn-off/turn-on had to occur. There was to be an overlapping time that both the old frequency and the new frequency could simulcast, to get listeners used to the new dial position, then eventually dropping the old frequency thereafter. Now whether these stipulations fell by the wayside or something over the years, I don't know. I doubt the composers of the Act meant for this transition period to take EIGHTEEN YEARS. I believe the newest date to sunset the old station is at the end of this year.
And to bring all of this full circle from the original post, remember that KNOK-AM/FM was a combo (970AM and 107.5FM) and KMEZ-AM/FM was also a combo (1480AM and 100.3FM) and, when Summit and Granum reached a deal to trade stations, the AM's stayed with their original owner, and the FM's were swapped (meaning 1480 was now sister to 107.5, and 970 was sister to 100.3.) Later, of course, CBS/Infinity bought both FM's.
The Ticket already surrendered 950 (the old KDSX-Sherman) to keep 1700...so there IS someone still paying attention to that obligation. And having 950 (and possibly 970) out of the way creates some leeway for KTON-940 Belton to move into Rockwall, Lancaster, or wherever they've decided it's going today.