So I think in this case the motion interpolation can legitimately increase the verisimilitude of the footage. The pace and fluidity of the movement being more natural is not a bad thing for the showing off the times, though it is important that it be noted it's a particularly poor reflection on the history of cinema and its cultural impact. The two thirds that are missing have the 1/18 of a second on either side there, so I think there's a particularly low risk in introducing misleading information.

My bigger concerns are actually the upscaling (a bit) and the colorization (more). The former, I guess if you're just sort of presenting this to create the impression of these people's faces and to enhance the immersion in the era for a modern audience, it's not that bad, but you'd want to be very clear what you were doing, and you certainly wouldn't want to say something like, "See what your great-grandfather's face really looked like?" For the colorization, I'd want to know what were the sources, techniques, and tools used. Those would befit from genuine historical research and could be actively misleading about what we're seeing, providing a false certainty in a way that motion interpolation mostly doesn't, and upscaling sort of doesn't.