Why are they underwater? The "value" of their options would have been the preferred share - common share price. So it would have been a fat haircut but likely still netted them some number > common share price, no?
Loom is an odd case because the timing of their last round was simply perfect. It was announced in May 2021, which means the terms would've been set in Jan or Feb, when Tiger and other firms were on a rampage and competition to get into rounds was at its height. That last $130m has to have been on very favorable terms, not just the valuation but e.g. no crazy liquidation preference. So, unless Loom's founders made some inexplicably bad deals, I'd expect even recent hires to still make a little money. Nobody should be getting zeroed out.