Very strictly speaking, I kinda agree. Western legacy media is the mouthpiece of the ultra-wealthy, and supports continued economic colonialism of the Middle East. That currently happens to coincide with Israel’s interests, so functionally they’re hard to tell apart.
However, I think saying they’re actually Israel’s mouthpiece comes dangerously close to some of the legitimately antisemitic deep-state conspiracy theories.
Maybe this is just semantics, but I do think the distinction is somewhat important.