I'm not surprised. The "logic" section of the LSAT (traditionally said to be the hardest part of the test) is much easier if you know some computer science/discrete math. A lot of questions can be quickly parsed into some sort of constraint satisfaction problem, and using the right tool (drawing truth tables/constructing a directed acyclic graph) means you can get to the answer much faster.[1] Since the LSAT is a time-pressure based test, this gives you a big advantage. Of course, the reading comprehension parts are still hard, and engineering gives you no advantage there. There's also lots of selection bias potentially going on - engineers who go on to take the LSAT are
rare. Who knows how that prior correlates with ability.
Somewhat relatedly, it's been well known that for CS PhD admissions, at least with native English speakers, the GRE Verbal is a better predictor of PhD performance than the GRE Math. It's unclear how much of this is top-end compression in math though (almost everyone going to a top CS PhD school gets a 790 or 800 on the GRE Math, so there's no signal left there, whereas verbal has a higher spread. A 720 on the verbal is 98th percentile).[2]
[1] I know this because in 2009 as a college senior, I took some practice LSAT tests, and found the logic section endlessly delightful and challenging in a timed setting - I was this close to applying to law schools before I changed my mind and did a CS PhD instead. I know it sounds like a weird choice, but 2009 was a weird soul-searching year for me for various personal reasons.
[2] All of this has changed since 2011 when the GRE scoring system changed to a 130-170 scale from the old 200-800 scale, along with changes to the test itself. All of my points are probably obsolete.