I also think the provider is being too pushy with this. I know how hard it is to run a privacy oriented service, especially when the community is full of skeptics, but some of the pressure directed here feels a bit aggressive from them. For example, see this Wikipedia listing they are pushing which keeps being rejected (for “not having reliable source”, since they keep citing their site as a reference).
Additionally, their constant claims of being open-source and not having “closed-source” servers are irrelevant, since if the client side is implemented well and audited to do what it is supposed to do, most E2EE services don’t actually need to show how their servers function (since a lot of these services actually have a threat model of third parties like AWS operating their infrastructure). This is a fundamental misunderstanding of how Proton and other services work, especially in their native clients.