Corroded alloy nipples

That is certainly corrosion damage...

and was most likely caused by CO2 and the amonia in the stans sealant. It most likely will not be covered under warranty. CO2, while an inert gas, certainly can be corrosive, as Fix the Spade noted. It is the main reason that CO2 tanks as used for paint ball markers an other applications, only have a 5 year life span without being tested to ensure the integrity of the tank. I've seen the inside of aluminum CO2 tanks that look just like that. Amonia will react similarly, but usually takes much longer. But what you end up with when you combine water, CO2 and amonina would likely be even more corrosive than plain carbonic acid. The fact that the CO2 and/or sealant actually got to the nipples indicates some flaw in your tubeless set up. I've been using alloy nipples on wheels set up tubeless with Stans sealant for quite some time and never noticed any corroding of the nipples.

In conclusion, yes the combination of CO2 and sealant likely had everything to do with the failure. That and the likelyhood that your tubeless set up allowed both gas and liquid leakage past the rim strip.

Suggestions:

1. Stop using CO2 to inflate your tires. Not only does it produce the effects that you've already observed, it can make Stans sealant pretty much useless. Check the Stans website, they highly recommend against using CO2.

2. Double check your tubeless setup. Make sure that whatever you are using for a rim strip goes completely across the spoke bed from bead to bead and is completely sealing the spoke bed. Or use a sealant that does not contain amonia. Other options are to go to a full on UST wheel, or use the split inner tube "gehtto" system. Either would ensure complete seperation of the sealant form the spoke bed.

Good Dirt