So... the party that holds the presidency and both chambers of Congress is the "opposition?" That's an interesting take on things.
Perhaps he means "opposition to authoritarianism," but the party of "I have a pen and a phone" and "We need to pass the bill to find what's in it" has it's own authoritarian tendencies. I'm NOT a fan of Trump, but the idea that this is a problem only with the Republicans is silly.
So is the idea that the dissolving of "mutual toleration" mentioned in the article is a one way street. There are plenty of interviews like this one https://www.nationalreview.com/2021/07/ive-never-felt-this-s... that express how norms on the left have also changed pretty drastically over the past few years. The government has been in multiple law suits with a group of nuns, called the "Little Sisters of the Poor," all of whom are celibate and most of whom are elderly, trying to force them to buy health insurance that includes birth control. Maybe that group of nuns is misguided, but how does the left demonstrate mutual respect? How do situations like that demonstrate "restraint in using their institutional powers?"