Yes Nixon withdrew American ground troops and ended the draft, to deal with domestic divisions the war was causing, that the left was furthering as far as it possibly could, even at the cost of destroying the Democratic party at the national level. But he did so because he saw how to keep SVN free without US ground forces, as the balance of the article describes.
And the congressional "string pulling" that undercut this strategy did not succeed until after the destruction of Nixon's presidency - not by Nam but by Watergate - and the 1974 radical congress that followed his resignation. McGovern lost in a landslide, when the peacenik platform was actually presented to the American people.
The radicals that let the Khmer Rogue take over Cambodia and the NVA take over SVN did not run on peace - the draft was already over and US forces had already left. They ran on their supposed honesty compared to Nixon's crook-ness. Then they sold several million people into communist slavery to justify their own past intransigence, throwing away everything Nixon had accomplished, because they didn't like who had accomplished it.
Woudl Kerry sell out Afghanistan and Iraq in the same way? He waddles. You do the math.