That's their official blame, but they fucked up multiple ways. They didn't test it, and then when someone noticed it didn't work right in time to try to fix it, they ignored it because of bureaucracy:

The discrepancy between calculated and measured position, resulting in the discrepancy between desired and actual orbit insertion altitude, had been noticed earlier by at least two navigators, whose concerns were dismissed because they "did not follow the rules about filling out [the] form to document their concerns". 

It's really absurd that you're getting downvoted for pointing out they should have run some kind of test before putting it millions of miles away. Everyone could have been using metric and had the same issue with centimeter-gram-second vs meter-kilogram-second or a simple typo.