They can probably find loop holes, like saying they do support many alternative browsers like Edge, Safari, Opera, Vivaldi, Brave, etc. . They just don’t want “insecure” and “outdated” browsers that support terrible stuff like ad blocking, but they can agree to support Firefox if Mozilla takes action to prevent “insecure” extensions like ad blocking.
But using the dominance of YouTube to influence the browser market is textbook anticompetitive, painting a huge target on themselves for regulators.
They can probably find loop holes, like saying they do support many alternative browsers like Edge, Safari, Opera, Vivaldi, Brave, etc. . They just don’t want “insecure” and “outdated” browsers that support terrible stuff like ad blocking, but they can agree to support Firefox if Mozilla takes action to prevent “insecure” extensions like ad blocking.