Interesting article, but not all that relevant to the pardons at issue. Why? Because the author references the “presentation clause” in Article I, ยง 7 of the U.S. Constitution, which refers only to the presentation of legislative bills, orders, resolutions, or votes to the POTUS that require the approval of both the POTUS and the House and/or Senate. It does not refer to actions that are exclusively within the power and authority of the POTUS, such as pardons and executive orders.
In my opinion, the POTUS has the absolute power to authorize the use of electronic signatures with respect to actions that are purely executive (congressional approval not required), unless otherwise prohibited by the Constitution or statute — there is no such prohibition. The only issue is whether there is a paper trail that establishes that Biden approved the pardons and the use of his electronic signature to formalize his approval - something we will probably never know for sure.