I'm not sure I agree with this take. Those investigations may very well take place, and the other members of the Biden family may be on the hook for crimes committed. (Not Hunter's crimes, but accepting illegal funds etc.) If Hunter is compelled to testify he can't take the fifth, because there's no possibility of self-incrimination. Furthermore, if he DOES refuse to testify (as I understand it), then he can lose his deal for the pardon.