Gasly sounded frustrated over the board radio because he had no room to swerve in front of Alonso. Sergio Perez was in fact on his left, leaving the Frenchman sandwiched between the two drivers. "Alonso was slightly in front of Gasly on the exit of the corner when both cars hit each other", the FIA statement reports. "The stewards consider Gasly to be at fault for the collision because he did not leave enough space."
The fact that Perez was on the inside of Gasly was no reason for the FIA to mitigate the penalty. "The stewards do not consider the incident to be unavoidable contact at the first corner of the first lap, because Gasly was not sandwiched between two cars when he hit Alonso's car."
Being the main culprit gets you a penalty
Race director Michael Masi says on Motorsport-Total.com that Gasly was penalised according to the principles they set out prior to the season: "After discussions with drivers and teams, we had to scale back the 'let them race' rule a bit. One point was incidents on the first lap. If a driver is the main culprit, it will probably lead to a penalty."
Asked for a comparison with the incident between Max Verstappen and Lewis Hamilton at Imola, Masi replies: "If two drivers are at fault, then it probably won't result in a penalty on the first lap - or if more than two cars are involved. If it's clear that one driver was at fault, then a penalty will follow."