It's incorrect to say," Ex-Jw's who say Jehovah is incorrect, are incorrect."
YHWH and Jehovah are not equally "correct" or equally "just as right." They are both equally NOT GOD'S NAME. They are both equally the guesswork of humans, equal assertions, equally incorrect.
It would be more correct to say that according to the Bible, a proper "name" for God doesn't matter. He would have used his power to preserve it, if it mattered, but he didn't. Therefore, the real issue is not which "handle" some sect gives to God, but whether or not it matters at all.
In the case of JWs, they claim that restoring the divine name is proof that they have THE truth. If a JW admits that Yahweh and Jehovah are equally as good, and that it doesn't matter which one you use, then "restoring" it is not proof of anything.
That is a big deal, because JWs have a core set of beliefs that they feel are proof of their sects belief.
Main belief: WTBTS is God's Organization, the sole channel of truth.
Why? 1) Only they preach the good news. 2) Only they have true love for their brothers. 3) Only they use God's "name".
Most arguments are not just about Raymundis Martini, but about #3.