They were not called until he was in serious distress and already on the ground, with a knee on his neck and bleeding from his mouth.
https://www.news.com.au/world/north-america/george-floyd-death-timeline-from-arrest-to-asphyxiation/news-story/3d574145a17045bb5d6c042f8df264ba
While the paramedics were checking for his pulse, which they did not find, the cop still had his knee on the dudes neck. He was already dead, how much resisting could he possibly be doing.