MM theory on dividends?

Is this statement correct on MM theory on dividends?

“Miller (of Modigliani and Miller) concluded that if investors face different tax rates on dividend and interest income, the advantage for debt financing may be reduced somewhat. This conclusion is supported by international capital structure differences as countries with favorable dividend tax rates tend to use less debt in their capital structure”

I *think* that the two propositions where either I) capital structure is irrelevant II) when taxes are present, 100% debt is optimal

So I would guess that this statement is incorrect, but this is a very late-night and not thought through conclusion. I would like to know the answer and explanation to this if you’ve got it!

This isn’t a statement about the MM theorem. It is a separate statement by Miller, and they are just noting that it is the same person. It is correct.

My question particularly is about taxes on dividends and interest income. I studied comparable taxes on dividends and capital gain and not interest income. How do you compare dividend taxes and interest taxes in context of what MM said?