Radiant energy travels through the air without heating it. It turns into heat when it contacts a cooler solid object.
In that sense, it does not directly heat the air.
However, a radiant panel set over a hide and the surrounding floor of a dark PVC cage will effectively heat those surfaces up. The heated hide and floor will warm the walls. Any air that comes into contact with these heated surfaces is also heated.
Therefore, you can get a boost in ambient temps from a RHP. The heated hide works to warm the air, as does the floor. The top of the hide may heat to 94 degrees, but a shot inside the hide, surrounded by heated floor will be a toasty 88 to 89 degrees.
Again, I ran these setups on terrestrial cages with great success. I'm a believer in RHPs and will use them in ANY sort of cage without hesitation.