Earlier quoted context omitted.
Not every business can afford to go one month without income. What's the best thing for customers? Have the business go bankrupt and irremediably lose access to the service?
It's 400 clients, not all their user base. They can handle the lost income from a small slice of their customers for one month. And if they can't sustain that, then it's even more imperative that those customers migrate away.
Fastmail gave 1 month free service to about 2/3 of our customers after a major disk failure that led to about a week of downtime for them as we recovered from backups in... 2005ish I think. Long time ago - it was a pretty major hit and the wave in income is still visible all these years later as a lean month where there's no renewals from that batch! Definitely the right thing to do though.