Not surprising; this is the stuff that replaced asbestos in the refractory industry. Hard to say if there is a real handling risk or just CYA due to the plaintiff's bar. The MSDS is an interesting read:
http://www.thermalceramics.com/pdfs-uploaded/msds/americas/201.pdf
Note the level of exposure for the rats and mice in section 11, toxicology....
200 fibers per cubic centimeter, 6 hours a day. It was probably hard to
see the rats in an atmosphere that dense <g>
The builder who submitted the last sample intends to enclose the material in an aluminum foil "envelope" (roll foil with neatly folded edges). A few panels under the front carpet get stainless foil, as there are several reported incidents of RV's burning through single-panel belly skin right behind the firewall.
Fresh news: Another RV builder and I ran two-minute burns on three samples last weekend, all enclosed in an Reynolds Wrap aluminum foil envelope. One was 1/2" Cerablanket. The other two were samples of the latest and greatest exotic, which we will call Brand A (yes, that's a hint...legal restrictions on the samples).
1/2" Cerablanket/foil and slightly thinner 10mm Brand A/foil exhibited similar practical performance, about 400F backside temp at 2 minutes and less than 140F for the radiant heat target at 6" distance. A different Brand A product in 5mm thickness didn't perform quite as well, but was still a very safe choice compared to the rubber, fiberglass batt/aluminized plastic, and polyester fiber/aluminum foil examples previously tested. Oddly enough, the 10mm Brand A sample did exhibit minor outgassing through a seam in the alumimum foil, and the outgass did ignite, burning with a weak flame much like a Bic lighter. Not significant enough for a condemnation, although not a plus. Given the insignificant performance difference, I don't see much point in fooling with the far more expensive product anyway.
Please remember my personal interest here. I simply don't want to see anybody burn to death due to a
bad choice. Some materials have been very bad indeed. I've avoided recommending a specific product, instead focusing on bad choice, good choice material
types. If a possible cancer risk makes you nervous, find another material and I'll be happy to test it.