I doubt he'd win Massachusetts in 1984, without Vietnam as an issue.
If Mondale couldn't carry Massachusetts, I don't see why McGovern would have, under the circumstances of 1984.
Despite that Reagan almost won all 50 states, and MA wasn't close in 1972, the 1972 election was actually more of a landslide.
That's true. I think McGovern carried Massachusetts 55-45, or something like that. But in 1984, Reagan carried Massachusetts 51-48, and I can't find any reason to think McGovern would have done better than Mondale in 1984, without the Vietnam War.
I find it funny that Nixon carried Rhode Island in 1972, even while Massachusetts wasn't close. I have always thought of those states as very similar politically, and can only imagine them being carried by different candidates if both states are very close.
1980 was another time Massachusetts and Rhode Island didn't vote the same, with Carter carrying Rhode Island by a decent margin, and Reagan narrowly carrying Massachusetts.