There's this thing called "character assassination". You cannot deny that an army of right wing operatives would dig deep into this persons life looking for anything to discredit them. This person and their family do not deserve to be raked over the coals for no other reason than for the right to cloud the issue and intimidate a witness.
Well, without scrutiny
you are in fact supporting the very issue you are concerned about, but, this is an attack on a duly elected President! He cannot defend himself, people cannot ask questions and motivations because, well, the secret accuser must remain so?
In effect, the President, his supporters and the ability of his government to do their job for the people is impaired and harmed by what is, at this point, a groundless accusation.
In politics or in a courtroom, we can't operate on the "Honor System" where any allegation is accepted as fact. He needs to come out and stand by his allegation in the open. Of course he will be scrutinized, it's politics and he could simply be a political plant or hyper partisan. Just as in the Kavanaugh Hearing, motivate will be and should be flushed out.