That's present on the 'original' Ehobby Tigertrack.

It's also presumably a carry-over from what the brothers' original decos were supposed to be, before the colour switch.

They also don't need to do a mass-run to test a colour/parts scheme, as that's what test shots are for. It'd also be weird to do one like that with the such a similar car mode.

Precedent also shows that a new character with some retooling, who's from the coveted s1-s2 cast, will get a new number entirely (the Datsuns).

Plus Sunstreaker is a nobody for the Japanese audience, so the only thing he has going for him is the license and that he's from year one.

Frankly, I could see them doing him as a Wheeljack remold/reshell, before using the existing Sideswipe robot tooling.