The need for moderate Republicans
Purity does not matter if we cannot implement our agenda because we lose winnable elections.
Republicans need to stand for something. The point of a political party is to advance a set of values, and if there is no difference at all between a Republican and a Democrat, then there is no reason to elect a Republican. But Republicans still need to be willing to have moderates represent the party. If the choice is between a moderate Republican who can defeat a liberal Democrat and a conservative who cannot, we would be better off with the moderate.
Take Jeff Flake. He was not perfect by any measure when he was in the Senate, but he was a consistent conservative vote. Before he announced he would not run for re-election, he voted with Donald Trump's position more than 90% of the time. Flake openly disliked Trump and repeatedly criticized him, so MAGA Republicans cheered when he announced his retirement. Trump bragged "I retired him" and said he was "very proud" of that. Who was Flake's replacement? Kyrsten Sinema, who opposed Trump's agenda in 2019 and 2020 and has faithfully voted for Joe Biden's agenda for the last three years.
Congratulations, Republicans. We made great progress. So much winning!
The reality is that it matters which party has a majority in the legislative body. The winners get committee chairmanships and the majority leader and/or speaker. Had we not had Mitch McConnell as the Senate majority leader in 2016, there would have been no hope to overturn Roe v. Wade because Marrick Garland would be on the Supreme Court. Even a “moderate” who annoys conservatives is better than a liberal Democrat who supports the Democrats' agenda.
We need to hold Republicans accountable and there are many times where a primary challenge would be appropriate. However, it is politically foolish to hand a seat to a Democrat, especially when the reason for doing that is loyalty or opposition to one man. Republicans need prioritize winning elections and getting conservative legislation passed, rather than focusing on loyalty tests to Trump or anyone else. It simply does not matter if we are 100% totally pure if we lose elections.