Your position is that Biden, on tape, bragged about getting the investigation cancelled, but he was exaggerating how big his role was, because it was the Obama administration policy to get it cancelled? I find that laughable. It sounds like you're looking for any rationale, no matter how far-fetched, to make Biden not have done what he clearly said he did.
Mind you, I'm a "both/and" kind of guy here. If it was improper for Biden to use the threat of withholding US aid to get the investigation cancelled, it is also improper for Trump to use the threat of withholding US aid to get the investigation restarted.
What I need to see, though, is something on Trump that's closer to what Biden said. Biden outright said he did it. Trump... if you read the transcript through "Trump is a horrible person" glasses, of course he's implying that he'll withhold US aid if Ukraine doesn't do what he wants. If you don't read it that way, though, if you don't assume that's the subtext, it's less clear that he's actually threatening.
He was describing an action he took as the Vice President while in a foreign country. That really doesn't establish his role in setting the policy, as one purpose of the trip would be to deliver the message.
There can certainly be evidence that he argued strongly for the policy, that he delivered the message says very little.
Even if everything were as you say (which I don't believe), it still would speak volumes that nobody saw a problem either with the message being delivered, or with Biden being the one to deliver it. Surely someone in the Obama administration understood the concept of "conflict of interest"... didn't they?
Mind you, I'm a "both/and" kind of guy here. If it was improper for Biden to use the threat of withholding US aid to get the investigation cancelled, it is also improper for Trump to use the threat of withholding US aid to get the investigation restarted.
What I need to see, though, is something on Trump that's closer to what Biden said. Biden outright said he did it. Trump... if you read the transcript through "Trump is a horrible person" glasses, of course he's implying that he'll withhold US aid if Ukraine doesn't do what he wants. If you don't read it that way, though, if you don't assume that's the subtext, it's less clear that he's actually threatening.