Over the last 12 years at all times I've had 4 to 7 people employed by me. Every penny they're paid is money I'm not paid. My income is exactly "what's left" and sometimes that's less than my employees make.
You're not wrong. When non-business-owners suggest to me that I should "just hire more people and grow" it makes me bonkers, as if it's that easy. You can't hire people you can't pay for, and you can't pay without revenue. (Or sometimes the ability to convince a bank or investor you'll have revenue soon, or just a big wad of cash.) And new employees generally draw paychecks for quite a while before they boost productivity. And when you use existing staff to train new staff, they too become less productive.
Please bear in mind I was responding to "their hands are full", and my point was none of us on a web forum know how full Tesla's hands are, or how easily they can respond to demand. That includes me. But generally, when there's strong customer demand, these problems can be solved. I think it's unlikely, as the post suggested, that it's a good idea for Tesla to reduce their expenditure of resources working on a potentially-profitable product to focus on another.