If the United States were to strip 40% of its population (targeted on an ethnic basis) of citizenship and subject them martial law, would you consider it a democracy?
The answer is obvious. You can pretend to be worried about credibility, but you know what you're defending.
I haven't so far defended anything other than the principle (in fact, merely the utility) of making arguments in good faith.
You could have initially made the observation that a large fraction of Israel's population lack voting rights, and all of those people share an ethnicity -- but you chose instead to make a stronger and more alarming claim that you knew to be wrong.
Arguing in good faith is a prerequisite of useful discussion, it's that simple. Until you accept this, statements you make will tend to undermine your position in readers' minds, not strengthen it.
The answer is obvious. You can pretend to be worried about credibility, but you know what you're defending.