I don't know if Twitter's particular length limit is applicable to interplanetary communication. It was originally dictated by the arbitrarily chosen data packet size for communicating with cell towers which in turn impacted how large SMSes could be.
Recently tweet limits were relaxed, but it still remains the normal to communicate "significant dialog" through image macros which are extremely unfriendly on transmission size and threaded discussions (multi-part tweets) tend to mesh very poorly with how the social features of twitter work, where certain chunks of the thread often get different levels of promotion leading to incomplete segments of the conversation being conveyed.
I don't really think twitter has any real advantage over any of the other social networks (outside of the explicitly image focused) except through its arbitrary payload limit which, as I mentioned, is no longer a firm limit and often comes with additional auxiliary payloads (like a linked image) to actually communicate - AFAIK the actual mechanics of how communication is executed isn't particularly well suited for this sort of lossy transmission, at least in any way that isn't matched by other social companies. It's much more likely, IMO, that mars based communication would just use emails since that transmission format already comes with the ability to embed images as needed and works well enough that it's survived decades of existence.