I'd imagine because of the talk from the then-incoming administration talking about how he'll go after their families unless his personal ongoing charges were dropped [0]. I would do the exact same thing if a vindictive POS was about to gain power.
[0]: "Trump threatens to prosecute Bidens if he’s re-elected unless he gets immunity" https://www.theguardian.com/us-news/2024/apr/30/trump-second...