The reigning champion still managed 142 miles per hour (230 km/h) on the Hangar straight during the final lap in a bid to hold off the charging Max Verstappen in second place.
Given the speed at which the incidents unfolded in such a short period of time, Masi had to step in for everyone's safety.
"I actually hopped on the radio to the two teams and three cars and asked them to slow right down immediately," the Australian said, "effectively to minimise the impact both on themselves, but more importantly on everyone else around them.
"That was an immediate call that went from race control to each of the teams individually."
After explaining it would have been "a bit irrelevant" to send a safety car given Hamilton suffered his puncture on the final lap, Masi tackled another decision from race control that left many people puzzled.
Whilst the Haas driver was shown the black-and-white flag for the initial incident, essentially a final warning for unsportsmanlike driving, he avoided a penalty for the repeat offence following a visit to the stewards post-race, to the confusion of many.
But Masi explained: "Following extensive discussions with the drivers throughout last year, one of the big areas the majority of them asked for is a clamping down of cars moving under braking.
"This is the first element of that we’ve seen of it this year and as a result, the first time it happened, the black-and-white flag was shown.
"On the second occasion, it was referred to the stewards for them to do a further investigation. The stewards gave Romain a warning in accordance with the ISC [International Sporting Code].
"We’ve agreed that we will discuss this at the next drivers’ meeting and go from there."
Grosjean explained he only did it because others in the past, like Max Verstappen, had escaped punishment, with the Frenchman now seeking a clarification
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