No, humans coordinate. The idea of dropping a tool of coordination because you think it's about the numbers and not the utility is a terrible argument. Yes Mars will not have a 24 hour day. That doesn't have a single thing to do with, "legacy timekeeping". Timekeeping was not built on the idea of a "24 hour day". Timekeeping is built on coordinating humans to accomplish things whether recreational or utilitarian. Right now, our best system is based on the arbitrary divisions of an Earth day cycle. The base features of seconds, minutes and hours work. The day length, which is only about 37 extra minutes, doesn't require a brand new system. Hell, an Earth day isn't a perfect 24 hours either. Drastically altering the system just because you're terrible at showing up on time for meetings is pretty dumb. Since Mars is going to be in tight communications with Earth, especially coordinating resources, why have drastically conflicting systems? People bitch enough if you only give imperial or metric measurements online, "Where's my favored unit of measurement? I can't convert it on my own!" You really think different methods of time keeping are going to work out well?

So no, my take on the argument was appropriate. Their stance was an absurd concept based in teenage destroy-the-system angst rather than taking reality as it is. If there's a truly better way of making sure two parties show up at the same "when", then let's hear it.