As @wiguy94points out, you're completely misreading the optics here. Vast majority of the baseball community, including Brewers fans, have sided with Burnes over the team.
You're right that we'd probably get a bigger return at the deadline. But I don't think it'd be significantly lower, particularly if Burnes performs closer to 2021 and/or wins another Cy Young in the process.
MAYBE we could make the playoffs without Burnes, but that would require A LOT to go right (Peralta staying healthy and pitching 160-170+ innings, Ashby overcoming the shoulder injury to return in May and pitching significantly better than 2022 as a starter, Lauer repeating his 2021-2022 numbers despite underwhelming peripherals, Miley staying healthy, Houser repeating his 2021 numbers in a swingman role, Gasser adjusting quickly to MLB and performing at an above average level, etc.). Not to mention the bullpen, which is unproven, and the offense, which lacks a true superstar, would probably have to take a step up. But World Series contenders? I don't see it.
To consider trading Burnes at the deadline, unless we're out of the playoff race entirely, I would have to see one of: Jordan Walker, Andrew Painter, Grayson Rodriguez, Marcelo Meyer, Jackson Holiday, Bobby Miller, Ricky Tiedemann, Jackson Merrill, etc.