Uh, the sheets leave a layer of wax on clothes, and wax is pretty damn flammable. (Cite: candles.) The ignition point is higher than you’d find in a (non-malfunctioning) dryer (cite: they don’t combust in my dryer), but that layer of wax does defeat the flame-resistance of clothing, by coating the fibers with wax (cites:
https://www.drifire.com/care-instructions
FR home laundering do's and don'ts | 2015-10-01 | ISHN)
The relevant ASTM standard costs $44USD to download as a PDF, and if anyone’s $44USD worth of interested, it can be found here: http://www.astm.org/cgi-bin/resolver.cgi?F2757