If they determined he wasn't drinking or doing drugs, they'd probably let him go. My dad is a retired cop so maybe (well, probably) there is some bias on my end.. I grew up around most of the guys on the department, sure there were a couple pricks but most of them were just normal guys when off-duty. Despite popular sentiment, they aren't out there looking to ruin someone's day just to get their rocks off.
The amount of paper work that needs to be done to write a speeding ticket is prohibitive to most cops to be frivilous. Maybe they'll pull you over for going 5mph over the speed limit at 2am just to verify you're not drunk. 9 times out of 10, if you are not drunk, you go with nothing but a verbal warning.