The other caveat is that it only works if you're embedded inside a solid object. ;)
If you're in free space, the surface can't shine its IR differently in different directions, so under FLIR it will just look like the average ambient temperature. This is no better than existing (cheap and light) space blanket camo systems.
Well, could be still useful for hiding things in bulk materials ?
From scientific uses (sensors, cables or supports not disrupting experiments) to smuggling/hiding listening devices/trackers or boobytraps in bulk shipments, etc.