I don't think you can describe it as "get[ting] rid of" former Nationalist troops. However, there is some truth to the basic idea that Nationalist soldiers fought in Korea. Since soldiers had to obey the chain of command, to some extent you may describe that as being "forced to fight", as well
The best example is the PLA 50th Army, which used to be the NRA 60th Army only a couple of years before the Korean War. This unit defected as a whole during the Liaoshen Campaign, at the desperate Siege of Changchun. Incidentally it was the first time an entire formation defected to the Communists during the Chinese Civil War. The PLA 50th Army were part of the first wave of Chinese units to enter Korea in 25 October 1950.
The 50th Army was formerly Nationalist China's 60th Army, which had defected en masse during the civil war.
- Mossman, Billy C. United States Army in the Korean War: Ebb and Flow, November 1950-July 1951. No. CMH-PUB-20-4. Washington, DC: Army Center of Military History, 1990.
Another example is the NRA IX Corps. This unit garrisoned Suiyuan at the height of the Chinese Civil War, and was surrendered when the regional commander, General Fu Tso-i, decided to turn traitor in the hopes of bargaining for some retention of power. The IX Corps was reorganised into the PLA 36th and 37th Armies. They were dispatched to Korea at Fu's instigation in 1951.
The pervasiveness of NRA soldiers in the Communist armies becomes treuly apparent when we look beyond the army formation. When they arrived in Korea in 1950, the 38th, 39th, 40th, 42nd, and 66th Armies had all recently integrated one or more formerly Nationalist divisions. In other words, in the first wave of Chinese intervention, every army sent into Korea had at least divisional strength in former NRA soldiers..
Great numbers of former Chinese Nationalist soldiers - sometimes entire divisions - were taken into the Communist armies. These former soldiers were used in Korea, integrated into the Communist ranks and kept under the watchful eye of the Communist officers.
- Appleman, Roy E. Disaster in Korea: The Chinese Confront MacArthur. Vol. 11. Texas A&M University Press, 2008.
Somewhat tellingly, two thirds of Chinese POWs in Korea opted to defect to Taiwan, the last bastion of Nationalist China, rather than return to the Communist mainland.