... and sunblock, like us puny humans with our problems with ultraviolet.
[Actually, I think the yellow suits and weird goggles *are* for environmental protection, but perhaps the googles do nothing.]
Of course to protect a puny alien a few hundred grams of protective gear isn't as fun as a device whose apparent mass is a kilogram or so that operates on a planetary scale (skinny alien ~ 6 x 10 kg, Earth atmosphere ~ 6 x 10^18 kg, Earth ~ 6 x 10^24 kg).
Especially when there is pretty much no plausible explanation for the device's operation. At least not one that I can think of that has mass scales of much less than Earth's atmosphere.
If the problem is "inside the immediate area" of the cave there are easier solutions involving large (as in 10^6ish kg outgassings of molecules that absorb the appropriate frequencies much as atmospheric gasses and vapours absorb most of the infrared spectrum. However, if they're in a cave, an even easier solution would be a controlled light source that simply doesn't emit photons in the dangerous frequencies, just like we do with the coatings on fluorescent lights or the quartz housings around halogen lamps.
I also can't think of why red (which is pretty low-energy compared to UV) would be dangerous to their bodies in ways that green (higher energy per photon than red) or ultra violet would not.
The last rabbit in my that is that their problem with red is purely psycholocigal, in the "DON'T LOOK AT ME!!! *smash mirror*" sense.
At a stretch, if you read "sponge" as in our sea sponges, and you think of "a problem with red" as a psychological rather than physical one, then maybe the sponge is a carrier of a viral plague that affects mammalian photopsins or the primary visual cortex. Squeeze the sponge and the next thing you know 24 hour cable news is panicking about yet another global pandemic. Squeeze a different sponge and a counter-plague virus is released eventually undoing most of the damage. Self-replication gets rid of the annoying physical problem of the small mass of the sponge the puny human is holding versus the large mass of humanity (~ 4.5 x 10^11 kg); viruses get their mass from the environment by hijacking the host's metabolism.