Based on our modern human culture rules? Nah, unless Vulcan ships return home every 7 years or only patrol the Eridani sector, Starfleet would have to accommodate nonhuman cultural practices . Its already too Western humancentric. By the 24th century Picard hooked up with an officer and no-one screamed 'regulations'. Chapel reports to McCoy not SpockYou know a really easy way to rebrand or (Jesus Fucking Christ) "retcon" Spock and Chapel not being in a relationship in TOS is simply on the grounds that Spock is, by that time, the executive officer of the ship, making any relationship not only unethically problematic but against regs.