Everyone here is commenting about overautomation, but this isn't an overautomation problem. It's a secondary sanctions problem. The developer isn't being banned for breaking Google's rules, he's being banned for having hired someone else who later broke those rules; and then that ban was transitively applied to their personal account as well. This is beyond the pale. Google should not have the power to decide who you…
But Google has its own reputation (and users) to protect. It's taking a risk whenever it allows a developer on its platform. If a developer with low name recognition uploads malicious software, it's not the developer's name that makes the headline.
Crucially, there's no information on what the employee (and later contractor) 'H.' did to get themselves banned. Or fired. From the OP's own timeline, the ban came less than two months after they severed their relationship with 'H.' Google isn't swinging around the ban hammer years after the OP separated with 'H.'
The OP's games could still include code contributed by 'H.' And 'H.' is apparently untrustworthy. Is that a risk Google should be forced to take as the curator of the Google Play store? I don't think so.