1. The amount of nonsense in this tweet is really astonishing. McGovern didn't lose because of his economic policy but Nixon used Feds to turbo-charge economy & create false boom (which quickly deflated after Nixon re-elected)
2. Also McGovern's economic populist message undercut when big labor unions, for complicated reasons, opposed his candidacy. Partly it was because on their issues McGovern was a proto-neoliberal (he would later become lobbyist against Employee Free Choice Act)
3. Nixon was successfully able to divide Democratic coalition on social issues ("Acid, Amnesty, and Abortion"). But here, the culture has changed & Dems consensus strongly pro-LGBT, reproductive freedom. Marijuana legalization looks like a winning issue (as it was in Canada).
4. Maybe the one salient lesson from 1972 is that if a left candidate runs, establishment Dems will go out of their way to sabotage the campaign (LBJ told Nixon he preferred him to McGovern). In that sense, Summers tweet is a threat.
5. Also, any statement Larry Summers makes against wealth tax has to be weighed against fact he benefits from current inequality since as university major-domo he was showered with plutocratic largess. Addendum: Here's a photo of Summers with Jeffrey Epstein. 
