Again, perhaps he reflected on how he supported his son in 2014-2016 and, while not illegal, he decided it wasn’t appropriate moving forward.
There is zero evidence of any similar activity or support during his presidency, which is when the new ethics rules were introduced.
of note, I read an article last night about how tragic what Hunter has done to his family is. admittedly, the writer's approach was very forgiving, but the timelines are what they are and of the sort that any compassionate human can to be somewhat sympathetic to.
basically, at the time when Hunter was taken on board at Burisma and thereafter through 2017-2018, as the record shows, he was also profligate and coked up and completely ruining the lives of everyone around him. It was so bad that there was an intervention - at least one - with Hunter tricked into coming to a birthday dinner… allowing himself to be checked into rehab, then blowing off to Vegas to party.
But even in 2015 Obama administration advisors knew that it was a bad look for Hunter to get involved with Butisma, to say the least, and asked Joe to get involved, but at the same time all of this was happening, Beau was going through cancer treatment, and Joe said he didn't have the bandwidth to deal with Hunter's BS and Beau's situation.
The upshot of the story was that, while there was nothing Joe could do for his prodigal son, he wasn't just going to abandon him, and so it makes total sense that he would take his calls, even despite knowing the risk, as opposed to pushing him away further.
The article also makes the point that Hunter is such a toxic personality that he makes other people do weird things. i. e. dating his recently deceased brother's wife ?! yikes. That is some pre Victorian area shit right there....
and so I guess there are three possibilities: one is that like Dennis Hopper in True Romance, Biden bit some kind of bullet for Hunter, creating some paper trail that brings him down.
The other, and more likely to me, is that with Obama era officials eyes on the situation + Biden being, as far as the record shows, a highly vetted public official whose affairs have long been a matter of public record - he won't be found to be personally connected to Hunter's downfall other than by having been a somewhat overly forgiving father.
The third option is the one that is all the right wing rage: Joe himself is a criminal mastermind.
TBD.