It’s an interesting tactic. Trump and MAGA may have wanted her to vilify Clinton as she “exonerated” Trump, but it is very possible that Blanche telegraphed he wanted a clean bill for Clinton, as well, assuming some value in giving the Clintons a reason to want to hold up this testimony as reliable. But, if the latter is the play, they may be misunderstanding how much (really, how little) support Bill Clinton has among Democrats now and so how little weight his endorsement of her testimony would carry. Blanche may also have calculated it is better for Trump if both famous presidents were cleared, not just his own client.
Interestingly, he seemed disinterested in her volunteered defense of Prince Andrew — but that was a topic that seemed important to her (probably because undermining the testimony of the now deceased Giuffre matters for her own defense).