Parts of this thread are interesting.
Slime appears to be an emulsified rubber, mixed with filler, fibrous material and more then likely some kind of high boiling alcohol to act as a coalescent. It remains a liquid until it gets to a hole, where the fiber apparently acts as a web to hold the emulsion in place until the water can evaporate and the coalescent can 'cure' the polymer. The size of the fiber limits the effectiveness of the product to curing leaks 1/4 inch across, although it's recommended for tire applications that if the hole is bigger, shove a stick in there and let the slime (or fix a flat) cure around the stick. May work, who knows?
Anyhow, the folks at Slime aren't recommending the product for air suspensions, but the guy I talked to really had never heard the question asked before. There could be potential problems with the air compressor (I'd leave that question to Eddie) however given the design of the struts there seems to be little likelihood of the product actually circulating through the system (being a liquid, and having the solenoids on the top of the strut, there seems little chance the slime will discharge out the air lines). Again, I'm not expert on that part of the system.
As for fixing the leak, it would seem that the biggest problem would be getting the product in contact with the area that needed to be 'fixed'. Slime, being liquid, would have to be rotated around the strut, while air pressure was applied. This should 'theorectically' allow it to find the leak and work it's magic. I would think that any aerosol product would be a better use for this application, as it would supply both the sealant and the pressure at the same time.
There appear to be quite a few tire sealent mfg, certainly more then I thought were out there. This stuff is widely used as a preventative measure for everything from off road bikes to heavy equipment. I suspect that it's use in the air bag, absent it's transfer through the compressor, would not only be useful, but would certainly seem to be able to extend the life of the rubber.
The admonition that once dry rot starts, it continues could be a good one. I do not know enough about the degradation of rubber to offer an informed opinion on that, however I would be cautious also until I found out.
My 0.02.