I guess it depends on what you are using the loop key for.
If you are only using it for a key, as specified in it's name, then it is just a wire from one contact to the other, such that removing it removes part of the connection from battery to controller (or whatever circuit it is part of). Can be used as a safety (like on racing motorcycles that require a lanyard to pull a disconnect if the rider comes off the bike, etc), or antitheft (pull the key off and the bike/etc is harder to use without the same kind of connector, if it's not a simple round-contact type you can stick a wire loop into). This is the most common usage I've seen here on ES, for instance.
If you're using it as a precharge key, that's a separate thing, and would also require a second key that gets plugged in either in place of it or in parallel with it to do the job of the other key, or a switch across the precharge key, etc. (but a switch would be silly since it's much better, cheaper, smaller, and more failsafe to use the switch for the precharge and the key for the conductor section). It wouldn't matter if the key was male or female for how easy or hard it would be to put a resistor into the contacts of the key, since that would go in the back of the key, where wires would have normally gone, and those should be the same for male or female or genderless types.
If it's for some other purpose, you'd need to define that to figure out why one way is used more than another.
BTW, the precharge resistor in an antispark connector can't protect against wrong polarity, unless you stop plugging it in before the main contacts touch.