“Is the auto pen allowed for pardons? No. It is not constitutionally allowed for

“Is the auto pen allowed for pardons? No. It is not constitutionally allowed for presidential pardons. Why? Because the U.S constitution requires the president to be present. He was in a different state on vacation”

“Article 2, section 2 grants the president the power to issue pardons does not explicitly state the method. However, legal scholars pass interpretations argue the pardons require 𝐭𝐡𝐞 𝐩𝐞𝐫𝐬𝐨𝐧𝐚𝐥 𝐝𝐢𝐬𝐜𝐫𝐞𝐭𝐢𝐨𝐧 𝐚𝐧𝐝 𝐝𝐢𝐫𝐞𝐜𝐭 𝐚𝐩𝐩𝐫𝐨𝐯𝐚𝐥 𝐨𝐟 𝐭𝐡𝐞 𝐩𝐫𝐞𝐬𝐢𝐝𝐞𝐧𝐭. Meaning the auto pen is not fulfilled in this requirement.”

More context:

An autopen signature without the president’s direct authorization or presence could undermine the pardon’s legitimacy. For example, if a president were incapacitated or unaware of the autopen’s use, it might raise questions about intent.

So if Joe Biden was not mentally fit coupled with an auto pen signature. The most likely legal outcome would be the pardon not being valid.