I doubt that they were gung-ho Christians. But by "converting" they also renounced modern all modern Western secular belief - in things such as individual liberty, equality, and free will - by submitting themselves to Islam and thus to sharia, Islamic law. Islam is both a political system and a religious cult, and they accepted it.
I think this is a terrible precedent, and I think we're going to see more and more kidnappings and attacks where the Muslims demand that their victims convert. After all, it was pretty easy in this case; while the reporters were roughly treated and no doubt uncomfortable and afraid, it doesn't even sound as if they were tortured or seriously beaten or abused. Just the threat of it was enough to get them to publicly renounce their principles, thus proving to the Muslim mind that we in the West have nothing that is really important to us and for which we will fight.
And it shouldn't be a surprise at all! They're just reliving their early history, aren't they?
It means nothing. Let's not get carried away because a couple of guys didn't want to die over a phony, coerced "conversion."
No "principles" were renounced.
These men do not deserve to be criticised for refusing to martyr themselves. They have families that are happy they didn't.