In context of parent post, I wonder if people realize github is not where git things come from...

"if you choose to control a machine account as well, that's fine, but it can only be used for running a machine"

I'm not aware that "running a machine" has a legal definition. I think it's fine, if you have a corporate account and a private email you are probably fine. I think they mainly have that as some sort of rate limiting legalese, to prevent abuse from "account hopping" i.e. abusing the github api or spamming, etc..

If your work account is a "legal entity", i.e. it is a person under corporate personhood laws, this definition also doesn't really hold water (both you and the corporation account count as legal persons, so this doesn't do much, other than the cost of an incorporation being non-zero). Just don't do weird things with your separate accounts, and actually keep them separate, and you're probably fine.