Wet/dries make less nitrate?

[Playfair]

This guy on another board was shunning those that said wet/dry filters are nitrate factories, which may have some truth. But he sighted this little tidbit as to why they produce LESS nitrate:

A biowheel or bioballs have a large surface interface with the atmosphere. Ammonia is a volatile liquid. When exposed to air, it will gas off. These biowheels and bioballs, by their very nature, will gas off more ammonia. With less ammonia being left in the in the system to produce nitrites, YOU WILL END UP WITH LESS, NOT MORE NITRATES.

Does this have any merit?