Whigh begs the question, why not change the arrival time to reflect this?
IF the flight is always early, it'll keep confusing ATC, ground services and people picking the pax up so why not make it permanent.
I suppose it does make the airline look good, saying "our flights are always on time or early", or they're tring to cover themselves on the odd chance they're delayed around 3/4 hoursto wriggle out of EU261