Not even close.
George Meany was a union boss, not an industrialist. Get your bad guys straight. There were sound reasons he was angry at McGovern, the delegate rules largely shut Labor leaders out of convention power, so the unions did not give organized support to McGovern.
The 1972 convention was very nasty, there were a lot of hurt feelings, and frankly McGovern had a lot to do with that. The delegate rules that he had mainly drafted after the '68 convention were a total mess, with all kinds of unintended consequences. As one result, most of the primary candidates - of which there were many - did not actively support McGovern as they otherwise might have. Big corporate money, however, was all flowing into the GOP coffers, often in violation of the law (though like the Watergate break-in that wasn’t proved until long after Nixon’s win).
This isn’t ancient history, I was actively involved in Democratic politics at the time. McGovern’s problem was that (a) he was a rotten candidate, and (b) he managed to inadvertantly piss off many of his natural allies. However, the party leaders hated Nixon with a passion, and did not set out to undermine McGovern’s election, no matter how much you want it to be so.