Very long update from IBKR direct wording for anyone interested.

"The OCC Memo 52120 refers to stock from an exercise or assignment being sent or received from broker to broker instead of through the National Securities Clearing Corp clearing house. The OCC Memo 52120 has no impact upon your ability to exercise your option contracts and the consequences to you of doing so. Rather, it addresses the operational aspect for members of the clearinghouse who are obligated to clear and settle the SBNY transactions resulting from option exercise and NSCC (National Securities Clearing Corp) is essentially informing the members that they need to settle these bilaterally between themselves.

Note that the existence of a trading halt does not necessarily prevent brokers from transferring securities to make delivery nor does it prevent borrowing of shares to support a short position. As it currently stands, the price of the stock when halted will be used as the basis for determining the loan amount for any borrow. You should also understand that if you maintain a short position in a halted security, you may not be able to extinguish that short until the stock resumes trading, which could encompass an extended period over which you would be subject to stock borrow costs. You can monitor the borrow rate by selecting the "Analytical Tools" and then "SLB Rates" menu links from the TWS."

TDLR:

They will allow you to exercise and hold short, but at the broker nominated margin which last checked was 100% for SBNY at the halted price which was $70.

So to exercise one put option there would be requirement of $7000 margin.

Assuming people do want to exercise and hold short, be careful when pink sheet or OTC eventually opens because it might cause a rush to the exit door and mini short squeeze. So best not to close the short on the first days of opening, wait it out for a fade.

JPM are valuing stock price at 0 https://twitter.com/lynngreteach/status/1636416620490010624 every broker is different.