What I figure is this:
If FR was some kind of private blog, then, hey, hells bells, anything goes.
But since FR holds itself out to be the premiere conservative site on the internet, and collects money based on that premise, it has a reponsilbility to not censor people who have what would be considered conservative views on the issue.
And the poll the last time I checked was something like 95% opposed to open borders and amnesty.
So it would seem there is something going on that is being withheld from us.