"It's true the CDC prefers virtual gatherings," So, you were wrong.Here's the actual guidance. It's true the CDC prefers virtual gatherings, but it also includes guidance on how to make large gatherings safer, and that guidance appears to line up well with what's reported about Obama's party: https://www.cdc.gov/coronavirus/2019-ncov/your-health/large-gatherings.html
It's also worth noting that this guidance is primarily for unvaccinated people. The CDC has different guidance for vaccinated people, which does not include any recommendations for avoiding gatherings: https://www.cdc.gov/coronavirus/2019-ncov/vaccines/fully-vaccinated.html
If the article is correct that Obama's guests will be required to be fully vaccinated, then it is that second link that applies.
But then you try to justify your error.
Who is going to verify vaccination? By a paper card? lmao!