Why not? A great many of the contributers on this forum are patently not engineers, however they feel free to give engineering advice. There are also a number of doctors on this site.
This is from the FAQ's, not that you'd have noticed them:
BioMech & BioMed: Stories related to biomechanics,
biomedical engineering, bionics, biomimetics and biomechatronics, as
well as sports fitness and nutrition. Please note, posts about the
medications that one is taking will be deleted. This is an engineering
site, not a medical one.
Main Entry: un·couth Pronunciation: \ən-ˈküth\Function: adjective Etymology: Middle English, from Old English uncūth, from un- + cūth familiar, known; akin to Old High German kund known, Old English can know — more at canDate: before 12th century
2 a: strange or clumsy in shape or appearance :outlandishb: lacking in polish and grace :rugged <uncouth verse> c: awkward and uncultivated in appearance, manner, or behavior :rude
— un·couth·lyadverb
— un·couth·nessnoun
I'd say this definition adequately describes our know-it-all, opinionated, rude Guest.