There is an interesting aspect about Heavy Gear as a game where the Gears are piloted by humans. Ignore the fact that it is really the computer that does most of the driving, a thing a bit higher tech than what Volvo and Daimler are demonstrating. So who can pilot a gear and who does it best? (Hint, in real life it is anyone!)
One fact that we accept with Gears is that they are mass produced on an assembly line, but they are still machines, each one vastly more expensive than equipping an infantry soldier. You don't throw just any person into your machine if you want it to fight at full effectiveness.
One key to understanding who can pilot a gear can be found in the mass production model of Gear construction. Like modern military vehicles there is always some ability to adjust seats but there are often limitations on height or weight for certain positions. Being outside those limits might make it impossible or just dangerous to drive or pilot.
This means that outside of fictional examples you have to be at least this tall to ride. You also have to be able to operate the waldo controls which means that Captain Hook need not apply. There are foot pedals too though like today's adaptive cars adjustments could be made for pilots with skills too good to give up. Limbs can be regrown in the Heavy Gear setting so an amputation might just be a temporary problem; "Don't worry hon. I'm sure they'll be able to grow you another arm in no time" – Heavy Gear Arena Core rules p29.
What about other factors? Speed, dexterity, and precision? Well, for that the women who apply for being Gear pilots probably have an advantage though with a large enough populations the split in skill between genders should be negligible. When it comes down to it it will be a competition for who wants to train and fight for the position more. Natural ability and skill is what will count the most.
In Heavy Gear Blitz we have chosen to have two levels of pilots; standard pilots and veterans to illustrate that the respective nations don't send out equipment with substandard pilots. There is also the Conscript trait that causes models that are out of formation to suffer a penalty for not being closely directed. This allows for sufficient variety for the game. Technically there is no reason to specify who is the pilot actually is though it is a lot of fun to put this level of detail into your army lists.
In terms of who can and should play the game? That's easy, Everyone! There is a discussion going on around tables and online right now about how gaming should be open and welcoming to everybody. Too often the actions of a few and the inaction of many cause many people who would otherwise join us in enjoying the tabletop action to stay home and give up, or never start playing in the first place. This is really important to remember that everything about gaming allows anyone, no matter what kind of physical body they currently inhabit, to participate. Mentally it's the same. Apart from the need to be able to read and understand the rules, which even the blind can thanks to adaptive technologies, your mental state when you play should allow you to enjoy the game without diminishing any other person's enjoyment of the experience..
There is only one type of person who should not pilot a gear, or a Heavy Gear army. If you read the article linked above then you should have some kind of an idea about who that is. Toxic people, who are a reality in all parts of life but unwelcome in social gaming. We as a community can work to be aware and promote a safe and open gaming space where ever we meet to play, for all gamers. I have been pleased to say that with my whole time with Dream Pod 9 at all the conventions and events I have never seen and online in our company forums I have met a great bunch of friendly and kind people. Lets all help make gaming a great past-time, and make sure that everyone is welcome to pilot their Gears.