The idea is that criticism of Iran from an Iranian-American would have more merit. However, we have no way to confirm the validity of this claim. It could very well be someone pretending to be an Iranian-American.

In my experience, I find people who are "former ABC-ian" to actually be very heavily biased, if not outright lying about ABC. Mentally, I'd say it's worth less weight than someone with no information.

They left because they were unhappy with things. The former British folks are enraged about human rights abuses and societal collapse in Britain. The ex-Christians will rarely praise the Bible.

Not that there's zero weight, it's still a perspective to consider. But it has to be fact checked thoroughly.

why should it not?

why?

You don't think someone from a country might know a bit more about it than the average person on HN?