As of yesterday I have 21,052 MQM (11,052 flown, 10k from AMEX) and 1,697 MQD on my status match. This morning I received the Platinum Medallion welcome email, the website shows me as Plat until 31-Jan-21, and I can make my Choice Benefit selection*. I will hit both 18,750 MQM and 2,250 MQD before my match expires, but it does really seem like the system doesn't care and counts MQM from all sources only.
*Is it right I could delay getting RUCs until 31-Jan-21 and have until 31-Jan-22 to use them? Coming from the UA world that's just weird.