while this hired man was supposedly choosing Trump's successor? Simply not credible. It's widely believed that Trump didn't want Pence, not his kind of person at all, and that Manafort along with Trump's family and others, helped push Pence on Trump.
But that this menial agent (by billionaire standards) would pick the Republican Party's mostly likely next president? No.
Remember, Pence was a Koch alliance-approved candidate for their man in the WH well before. So was Paul Ryan and so was Orrin Hatch, for #1s, 2 and 3 in the presidential succession.
A number of those who were first named to Trump's cabinet, to act as agents of destruction of government from inside (and thus incidentally in line also), were also positioned by or acceptable to the Kochs and people like them.
Both SCOTUS nominees were ALSO provided to Trump by the Koch alliance-backed Heritage Foundation, on a list that was pre-approved by the Koch alliance (Kavanaugh was approved and added later).
These people, and others of their sort, own and control the Republican Party. None of that's coincidental, and the idea that the right's #1 presidential successor, especially given the extremely likely event that Trump would be removed from office, was not their choice is simply not credible.
Another thought is that, though Manafort is strongly believed to have been serving Russia's interests as Trump's campaign manager, so far Pence's only known connections with Russia are via the inevitable proximity through his presence in the campaign after being named VP. If hired-man Manafort chose Pence (impossible), it would be reasonable to think Pence was actually Putin's choice. And what would the Koch alliance of several hundred (at least) American wannabe centi/billionaire kleptocrats be doing while that was going on?