Well, let's think about it in terms of an example outside the fitness world.
Let's say that I was going to give you 90% of my yearly salary. Might sound good huh? What if I said I only made a $100. Not so excited now are ya.
Then what if I said I'll give you 1% of my yearly salary, but I make $5 million a year. That's a lot better.
So, a large % of a small # is still a small #. Yet a small % of a really large # will come out bigger in the end.
Just the same as with exercise. While we'll burn a high % of fat at lower intensities, we'll burn a high calories from fat a higher intensities eventhough the % is lower. Make sense?
And besides if these people want to debate it, just agree and say "Yup, let's go with the lowest intensity possible, sleep, and we'll be burning the high % of fat".
And to go on further looking at cardio as a means for fat loss isn't the right way to go about it. I'd go into the reasons behind it, but I replied to the other post about this the High vs Low Intensity one.