It's not "either / or," but should resoundingly be "both / and."
If the Dems were not a party run by corporate stooges, they WOULD indeed both walk, and chew gum, at the same time.
They would HAMMER AWAY at Trump's own on-the-record past statements in support of Single Payer and universal coverage, while promising that whatever Trump does, the Dems will require every Dem candidate in '18 to pledge to support Medicare For All, and push it forward with what will be their new majority.
AND, they would use every procedural and mass pressure tactic to block the Gorsuch nomination.
These would be but two parts of a broad strategy to block the recidivist agendas of the extreme Ayn Randian corporatists, white supremacists, and religious nut-cases that have coalesced around Trump, while focusing mass attention on their revitalized agenda of putting programs back in the service of common people.
Too bad the Dems are themselves a party run by "moderate" corportate stooges... but there is no REAL reason why anyone needs to choose between promoting Medicare for All, and blocking Gorsuch.