The NI thing is realistically just for an internal US audience (people of Irish Catholic ancestry who generally vote Democrat - hence the need keep them sweet). Nothing to see here.
But certainly Biden sees the EU as politically and economically more significant than the UK. Why this might surprise anybody remains a mystery.
So a conglomerate of 27 Nations that are generally all in recession to some degree or another, that are unable to make any political decision within anything less than 6 months without someone breaking rank or publicly disagreeing with the decision. That is led by a succession of political nobodies of limited wit, intelligence or capability is seen by Biden as more significant than the UK ?
That says a lot about the capability of Biden.