I can confirm the letter was real. The day Mark released it, TDA went from disallowing purchases to allowing purchases.
All suspended securities are automatically DTC chilled.
It's up to each broker on whether or not they will still allow purchases.
TDA is usually very stringent when it comes to this. I'm surprised they are allowing buys on other previously suspended grey sheet stocks, but if they have the ability to clear trades outside of the DTC they will allow it.
I suspect the DTC chill was reinstated quite some time ago. MIKP was one of the approximately 100 PK companies that sold unregistered, non exempt shares to Fairhills Capital, aka E-Lionheart which illegally sold them on the public market. The companies and Fairhills improperly claimed exemption under Reg D, Rule 504.
The SEC filed suit against Fairhills/E-Lionheart listing only 10 of the 100 companies as representative examples (the worst offenders). However, virtually all of the companies known to participated have either received DTC chills or DTC Global Locks (complete suspension of all services except custody).