He’s not being run out of the project… yet.
To be honest, to me this all sounds like sociopath behavior to throw politically-inconvenient people under the bus in desperate self-preservation, and hoping this would intimidate anyone falling out of line.
Everyone in that group should present their immediate resignation. Shameful.
Things should be put into perspective. The cost per user is actually the fixed monthly cost of operating an instance divided by the average number of active users.
In the discussion you linked to, there's a post on how Lemmy.ml costs $80/month + domain name to serve ~2.4k users. If we went through opex/users metric, needlessly expensive setups with low participation would be a justification to ask for more donations.
Regardless, this is a good reminder that anyone can self-host their own Lemmy instance. Some Lemmy self-host posts go as far as to claim a Lemmy instance can be run on a $5/month virtual private server from the likes of scaleway.