They do not define ‘conservative” the same way we do.
That explains it.
Ugh! It’s not the WaPo, but the Monkey Cage and James Stimson is a researcher. Please read the article, pre-opinions are especially subject to high volatility and low-reason.
Yes, remember that when the Soviet Union was still around, the hard line Communists were described as “conservatives”. One key to cracking the liberal code is that conservatives are always the bad guys, no matter their actual ideology.