not a fair comparison, TBH, because /bin/cat is running privately, whereas the interactions Mozilla writes about are presumed to be with third parties

comparing with GnuPG or GNUtls might be more fitting: suggesting that using it to send encrypted data to third parties would grant GNU access and permission to use the (plain-text) data you sent would be insane and outrageous

but it's very troubling that Mozilla might consider itself entitled to see and use your end of E2EE information, even the information that use send only to your own servers through it