My instinctive answer to the question "did he?" is: Why would he? Biden is not a strong opponent, so what's the point of taking him out? It's what other Democrats want to do. Why would Trump want to help them? My hypothesis is that Trump has a more complex game that his opponents do not understand and that they are therefore making awful blunders.
Back to Smith:
[T]he backdrop of [the Democrats] effort is far more complex and convoluted, connected not just to Trump’s phone call with the president of Ukraine and related evidence but the three-year war of attrition the Democrats have waged against the president. Their main instrument was the Trump-Russia collusion story... [but] Ukraine was always at the center of the Trump-Russia affair....