While I can't defend Biden's debate performance, we can't understate the pitfalls of debating someone with no incentive to adhere to facts or decency. Reminds of why legitimate scientists usually won't debate creationists or climate denialists. The denialists play by different rules.
Scientists follow a systematic approach to building knowledge, and speak from empirical evidence. Denialists grab whatever argument supports their conclusion, regardless of relevance, accuracy, or whether the arguments are consistent with each other. That's Trump method.