... untested nature of preemptive pardons ... Pardon them from what?
I have yet to find the text of the actual pardons.
Nope on "preemptive pardons".
Presidential pardon is "granted in recognition of the applicant's acceptance of responsibility for the crime and established good conduct for a significant period of time after conviction or release from confinement."
Note the key word "AFTER conviction or release from confinement". 
Biden named individuals have not been charged, convicted and sentenced nor filed applications to establish "acceptance of responsibility for crime" (As that's what pardon is based on ... "acceptance of responsibility for crime"). I anticipate Trump administration immediately filing legal challenge as there is no such language under presidential commutation/pardon requirements - https://armedpolitesociety.com/index.php?topic=70274.msg1457165#msg1457165
Well, It's more complicated than that. The quote you provided is from the "Application for a pardon". CFRs (Executive branch rules) say that a prisoner can not
ASK for a pardon unless they accept responsibility for the crime. Those rules are silent on whom the President can give a pardon to. And even if they were not, there is some real question about the chief executive's ability to waive CFRs if he wants to. A CFR is NOT a law, and while they are often tied to a law, they are not themselves a product of legislative function, and are under the purview of the Executive Branch. Additionally Presidents routinely grant posthumous Pardons for people they feel have been wronged in the past. These folks are obviously not accepting responsibility for anything.
The COTUS only says:
The President shall.....have Power to grant Reprieves and Pardons for Offences against the United States, except in Cases of Impeachment.
Timing is not mentioned. There is some case law on the subject: In Garland, 71 U.S. at 380 (1866) SCOTUS held that a Pardon can be issued anytime after the
commission of the crime, Which this certainly is. There is no need for formal proceedings to have started. (For Example, Ford Pardoned Nixon before any formal charges had been filed, and the matter was dropped).
So there is some question as to whether these pardons would stand up. There is precedent and case law that the President does not have to wait for a court case or conviction, and certainly not an admission of guilt to issue a pardon, but it hasn't really been tested in court. There is also the open question of whether the President needs to pardon a specific "Offense against the United States" or if these blanket "anything this guy did" pardons will stand up.
Hence my comment on the "untested" nature of the pardons.