Why would it be unreasonable if someone (let's say Biden) argues that it is good policy to close the borders, but they are also on record as saying such policy was xenophobic hysteria when Trump did it? Unless they would admit to being wrong and explain why they changed their minds, it is quite blatantly unwarranted hysterical panic (and xenophobic, I guess), or unreasonable policy based on politics and not science.
The way you phrase this, it sounds a bit like "Have you stopped beating your wife?" and I'm not sure what you really want to ask.
Is it "Should Biden give an in-depth explanation of everything he's ever said about border closings, and help resolve any seeming conflicts between things he's said at different times?"
My answer to that would be No. He's neither a historian nor a teacher not a political pundit. If you honestly want to understand why a president (or a teacher or a parent or a posek) would give different responses at different times, you probably need to analyze that yourself, or query others who have the time to analyze it.
Or are you asking "If Biden doesn't explain all his thoughts on border closings, should we conclude that his decision-making is unreasonable?"
Again, I would say No, that seems like a rather superficial basis for drawing such conclusions.
Or are you asking "Why was Trump castigated as xenophobic when he announced border closings, and Biden is not?"
That's an interesting question, which Psaki partly answered. Just look at the details of communication by the two presidents.