Could you point to anything that even suggests you need 2 hands to load the hand crossbow?
I can point to the facts that the hand crossbow doesn't have the 2-handed quality, and the ammunition property says reloading is a part of making an attack with the weapon which since it isn't 2-handed only takes 1 hand to attack with it.
This also applies to blowguns and slings.
The fact that the current edition of D&D is intuitive. If you can clearly show it takes two hands to load a crossbow, hand or otherwise, it takes two hands. You would have to prove at the table you could load a hand crossbow with a hand crossbow in your hand to get that one by me as a DM. No DM should allow two-hand crossbows with Crossbow Expert bonus action save perhaps every other round according to drawing action. They have to clear a hand to load the hand crossbow.
It shouldn't have to be written down same as they don't have to write down you need legs to walk as a humanoid.