Renfroe is a short-term cost but the Brewers had very limited flexibility heading into the offseason. Offloading that $11m gives them the ability to shuffle those funds around in the short-term. We'll see if that was the right decision or not but it makes sense from the team perspective.
As for trading one pitcher, it really depends on the return. If Arnold subscribes to the "bite of the apple" approach, the 2024-onward Brewers could easily be a better team if one of Burnes/Woodruff is traded while the other is extended.
To me, the biggest question mark is pitching development. The Brewers obviously had an amazing run of developing Burnes, Woodruff, Peralta, Hader, Lauer, etc. Can they do it again? If they can, trading a starter today makes a lot of sense and is the Brewer equivalent to what the Tampa Bay Rays do on a near-yearly basis. It's not great from a fan perspective but it's the reality of the game (and at least the Brewers post a respectable payroll YoY, unlike the Rays).