Bitmine has no debt, and theoretically, as long as Tom Lee can hold on, it can be considered a non-redeemable closed-end fund.
He has no reason to "force a sale of tokens." The only problem is that if it remains at a negative premium for an extended period, refinancing will become difficult, making it impossible to continue buying ETH to increase NAV, and the DAT flywheel will stall.
Some have also mentioned whether Bitmine might sell ETH and use the proceeds to buy back shares.
Saylor actually mentioned this, saying he would consider this possibility in the future because mathematically it could indeed increase the BTC content per share. However, the problem is that doing this during a market downturn would disrupt DAT's long-term narrative; this isn't arbitrage, but a narrative breakdown.
Therefore, logically, this wouldn't be done. Without leverage or debt, it could hold on indefinitely, even if it remains underwater, waiting for the market to recover. Historical experience tells us that as long as you hold on, even shamelessly, most will eventually survive.