Not to detract from your point that it took them a while to find troops willing to actually follow their orders, but you got some details wrong. Neither Liaoning nor Shaanxi were military regions at the time, Liaoning province belonging to the Shenyang Military Region and Shaanxi being part of the Lanzhou Military Region. The troops that were finally called in were part of the Beijing Military Region, mostly from Hebei province (24th, 27th, 38th and 65th armies) and Shanxi (63rd army). (Note that Shaanxi and Shanxi are different provinces.)

Also, even they weren't particularly loyal: https://en.wikipedia.org/wiki/Insubordination_in_the_PLA_dur...