They aren't going to run the site for free. They need to earn revenue from it to stay afloat and earn a living. They will monetize it somehow - ads, subscriptions of some sort, some other manner. Maybe they will sell it outright and move on to some new venture. But they will find a way to monetize it now they are not getting salaries from Stripe.
They can draw salaries from somewhere else and use a portion of that to run the site for free.
The main purpose of the site is the discussion forum, which can't be a static site.
$1000 a month on servers would do it. They could probably do something premium $10/m to pay for it.