not allowed to enter NZ for being gay or political views ? :(

A million variables in things like this.
Being gay doesn't mean much in most countries and being deported from a country for being gay is less than likely to do much in most other countries.
Political activism is another thing as many countries don't want people who could cause problems.

It does make sense. Being gay has nothing to do with it.
The reason would be due to having written about human rights and then being denied entry because of this.

Iran does tend to get a little shirty when it come to people who attempt to counter their version of what should be, but even that would likely have little effect on entry into New Zealand.
There has to be more.

I agree with Fred in that there may be more.
The process may well be just a necessary formality for Immigration records or there is something you are not divulging.

Considering enormous LGBT rights in New Zealand and freedom of speech, the entry shouldn't be a problem.

Definitely won't be because of any issues arising from being gay -  it is very unusual for British citizens to be denied entry into NZ (NZ has a very high British population).