The nozzle will hit that temp, but air temp will be much closer to room temp. A porous and poorly insulated fabric enclosure will probably not add more than 10 C temp increase.
Air temperature is not the issue and is not how 3D printers catch on fire, I should have clarified in my previous comment.
Nozzle clogs can happen frequently, and if left unmonitored, can quickly turn into a disaster. If your nozzle is clogged it can essentially destroy your printer and cause an electrical fault that can set the printer on fire.
Printer fires are a lot less frequent in recent years than a decade ago, but it can still definitely happen.
A nozzle clog won't set a 3d printer on fire either. It'll make a good mess of the hot-end. There'll be a bunch of charred filament, and heat creep will clog the nozzle nicely. It won't however magically get any hotter than it does while printing with an unclogged nozzle.
What does cause fires is failed thermistors. These days most firmware will detect unreasonably high or unreasonably low temperature readings and turn off the heaters. You thermistor can still however fail with a reasonable reading if you're very unlucky.
Another factor is MOSFET failure. MOSFETs have a failure mode where they can fail closed. This can turn a heater on permanently. Modern firmwares will detect the temperature going unreasonably high, but most hardware is not set up such that the firmware can do much about it.
