There are other IBKR-specific rules to consider in this scenario.  In general, IBKR would not have a special rule for long positions in stock trading below $5, as long as they are exchange-listed. Once a stock is delisted from one of the exchanges and moved to the OTC market, it would be subject to a 100% margin requirement, since the stock would no longer be considered marginable. 

Also, for long positions, the maintenance margin requirement is 30% of the stock value or $2,000, whichever is greater.

For short positions, the maintenance requirement on stock greater than $5, is $5 per share or 30% of the stock value, whichever is greater.  For short positions in stock where the last sale price/share is less than $5, then the maintenance margin requirement is $2.50 per share or 100% of the stock value, whichever is greater.