Whether Medicare for all would be inflationary or deflationary depends on the details of the law and its real-world effects. For example, it would eliminate almost all of the private administrative bureaucracy and decrease overall HC spending (both deflationary) but also introduce new dollars (inflationary). But remember, increasing money supply =/= inflation per se. It depends how productively those dollars are being employed. My guess is there would be an initial deflationary shock but maybe some inflationary effects in the long-run as premiums are spent elsewhere and former insurance sector employees find jobs in new industries.
Ideally, I think a payroll tax-cut should be passed with Medicare for All and then additional (progressive) taxes should be levied down the line if inflation does materialize.
As far as “playing defense”, the right is going to conjure the greatest possible boogeyman no matter what we propose. The Fox News base literally believed the ACA was going to bring on full communism. IMO, galvanizing citizens to actually come out and vote should be the focus. Honestly what is going to get disaffected voters to the polls? “Free healthcare, no questions asked” or Klobuchar’s “expanded Medicaid option with premiums capped at 9.5% of family income”. Both are Venezuela to Fox, but at least the former doesn’t put your average voter to sleep.