There were two men running in front of him for a while (and both just stopped eventually and just dropped off) - was it to "pull" him in their slipstream?

Partially. They're called rabbits[1] (or pacers) whose official role is to run a specific pace, who help encourage a fast race overall rather than a slow buildup with a fast kick.

[1] https://en.wikipedia.org/wiki/Pacemaker_(running)