Wha-? That was written by a police officer?
I can tell him why the driver was staying at 70. He was thinking: "Oh, no, there's a cop car behind me. I'd better not go over the speed limit. I don't want a ticket." That's why the driver was going 70 and no more.
Once I came across a line of cars going slow on the highway. I sped past, not realizing they all were driving behind a cop and the speed limit was 45. (Doh!) I slowed down, but not below the speed limit. The first thing the officer said when he pulled me over was: "Let me ask you a question - When you saw me, and you slowed down, why didn't you slow down to the speed limit?"
Read what you just quoted, the cop wasn’t upset at the man doing only 70, he was upset because the man was doing it in the wrong lane, and causing a dangerous traffic situation.