Protecting your name is perfectly fine. You're allowed to make a fork of Firefox, you just can't call it Firefox or use any of Mozilla's branding. You're allowed to fork the open source part of VS Code, you just can't call it that or use Microsoft's branding. etc. etc. - you're free to do with open source whatever the license allows, but you're not allowed to use the original name or branding because you have zero rights to those unless the license explicitly stipulates how the name may be used by forks (like how tons of folks use the "Linux" name, and all of them do so with explicit written permission from the Linux foundation, as they own that name as a trademark)
That's not the issue here. VSCode and FireFox are false equivalents. Even if you'd rebrand the fork, Signal forbids non-official clients/builds from connecting to their servers. Enforcement has been selective but the last official word AFAIK is that you are not allowed to fork, rebrand, and distribute a client which alllows you to chat with Signal users.
Mozilla still allows you to install and download add-ons and use other Mozilla services like VPN and Relay from your LibreWolf build.
Two wrote a two-part complaint, one part about clients, and the other part about Signal going after people using the Signal name. My comment was only about that second part (hence why it starts the way it starts).
