Unfortunately this is not enough. A malicious Signal server can mount a timing correlation attack and infer the social graph of an user. Having a centralized server makes it more difficult to mitigate such risk.
Then yes there’s EEE danger. Hopefully the Mastodon developers will resist that.
Unfortunately developers can do very little to prevent that.
EEE works by first attracting a large userbase into a service and later on prevent them from leaving.
It's up to instances admins and users to defederate to prevent EEE.
This is debatable. The GPL allow redistribution of a given version of the software without additional restriction. If the user receives that copy knowing in advance that redistribution will lead to retaliatory actions this can be treated as an additional restriction.
Context is important. It's possible that the software is distributed without any warning like that and that the termination of the support contract is done without citing the redistribution of previous versions as a reason.
OTOH if the customers could prove that there's widespread knowledge of the retaliatory termination that could be equivalent to a (non-written) restriction that is indeed incompatible with the GPL
Terminating a support contract, in itself, is not a GPL violation. The restrictions only affects the ability to receive future updates.
Edit: Red Hat indeed claims that no GPL violation is happening, yet they inform their customers that sharing updates leads to contract termination, which clearly breaches the GPL at least in spirit: https://sfconservancy.org/blog/2023/jun/23/rhel-gpl-analysis/
Indeed. If a big instance like lemmy.ml was to be shut down all the communities would be lost. This is simply not sustainable. Why would users put effort building a community if it could be gone at any time?
Does OrganicMaps have editing abilities?