I find it easier to distinguish "O" and "0" in fonts that distinguish between capital letter "O" and number zero "0" by putting a dot or something inside. It is already annoying, when you need to guess based on width or other shape between the 2, because that assumes, that you are seeing both at the same time, looking back and forth between them.

Additionally "I" and "l" look way too similar.

So I think "Unambiguous Letterforms" in this case not necessarily true.