Whatever way you looked at them, the mirrors mounted on the Halo device - and in particular the mounting itself - appeared to be more about aerodynamics than Sebastian and Kimi seeing what was behind them.
Unsurprisingly, rival teams raised their objections and in the end the Italian team was told that while they could continue with them for the remainder of the weekend, they were to be removed after the race and not seen again.
The FIA's race director, Charlie Whiting, explains why.
"It's a liberal interpretation of the word 'mounting' because that's how they become legal," he told reporters. "The interpretation hinges on whether we think that's a mounting or not. We somehow think not.
"They think it contributes to the rigidity of the mirror," he said of Ferrari. "I doubt they would be there if there wasn't a measurable aero advantage, but these days that doesn't have to be big.
"We sent a technical directive a few weeks ago in response to a number of questions from other teams about the principle of mounting a mirror on the halo was acceptable.
"We answered yes, and gave a few stipulations, one that it has to be a mounting. It's just a matter of interpretation and such a tenuous interpretation is not something we're happy with."
Though the mounts do not actually contravene any of the current regulations, when asked if they are banned, Whiting said: "Yes, you could say that", adding that the Italian team was allowed to use them for the remainder of the Barcelona weekend in order that the FIA be shown as being "reasonable" when there has not been a clear and deliberate flouting of the rules.