Runner collides with umpire

[Cecil4]

Here is an old story I came across, not involving me. Interesting discussion?

R1 on 2nd. Ground ball headed for left field, R1 heads for 3rd, BU cuts behind her toward infield. F6 makes an amazing play on ball, jumps up and chases R1 back toward 2nd. BU still cutting in and after 1 or 2 steps, R1 runs into BU. F6 tags R1 at collision point, 10 – 15 feet from 2nd. BU calls dead ball, confers with PU.
They decide it was an umpire mistake, misjudging the play and R1’s speed; causing jeopardy for R1, who might have made it back to 2nd. DC disagrees, but BU rules “part of field” applies to ball, not players. Based on jeopardy from umpire mistake, BU places R1 on 2nd, BR on 1st.

Maybe lots wrong here, including whether jeopardy requires a changed ruling.
What are your opinions?