To me, that's fine. Guentzel's next contract is potentially more harmful to Carolina's future than a lost 1st round pick.
Carolina isn't doing anything unprecedented here. Washington didn't buy high priced rentals until they made that one exception (Shattenkirk). St. Louis ended up doing it just one time as well (Miller). Ditto Tampa (Savard), interestingly.
While on the subject of conservatism, aggressive GMs over the years have included Sweeney (Nash, Bertuzzi, Orlov), Chevelydayoff (Stastny, Hayes, Monahan), Dubas (Foligno, O'Reilly), Drury (Copp, Tarasenko), etc.