Biden could approach and pay respects, but WAS NOT allowed to 'lay' the wreathe
For comparison, here are past presidents, actually elected and recognized by the US military as their commander in chief. Wreathe is presented for the POTUS to lay, rather than already there to begin with.
Here's Trump
And Obama
And Bush
And Clinton
And Reagan
Only Biden was denied the laying. Could approach and pay respects, but not lay it. Aligns with being a foreign dignitary rather than the POTUS.
If you arrive on a day that is guaranteed to have a ceremony conducted whether you show up or not, there's going to be a wreath there already. This was Veterans day. Likewise on memorial day where Trump shows up 30 minutes late to the actual ceremony.
But on inauguration day, or like with all the other links, you're the ceremony, and you're laying the wreath. This was basically Biden's day yet he didn't lay the wreath.
I'm pretty certain that by now everyone on active duty has seen the video of biden calling them stupid bastards. That means something.