The point isn't that they never publish an opinion piece, it's that they do publish investigative reporting, like this:

https://www.cato.org/blog/why-nsa-deleting-call-records

You also get pieces like this, which are full of factual information whether or not you agree with their policy position:

https://www.cato.org/publications/policy-analysis/new-nation...

And it's hard to see which "corporatist agenda" pieces like this are pushing:

https://reason.com/2019/11/21/with-this-forfeiture-trick-inn...

Which isn't to say that they're unbiased. Everybody has an opinion. But everybody has an opinion; that's why you need more than one news source.