So he did put his foot down.
In other videos it is clear that Biden put his left foot down, came to a stop then forgot to take his right foot out of a basket type thing on the pedal. I wonder if, in the gym, someone helps him put his foot into and out of the straps on the pedals of a stationary bike.
It also looks like everyone else was turning right but Biden went straightforward to where the people were gathered. From their comments, these people appear to be supporters of Biden. Perhaps press.