This is where it is most convenient to use the Royal We. He COULD just be talking about himself – but he could ALSO be implicating Gertrude in the blame portion – when “it will be laid to us” maybe he’s really suggesting it will be laid to her.
Certainly only a fool would believe that Claudius has let Hamlet roam free out of love. Who would he think he’s fooling? Has he been playing the “I love my nephew so much” card with Gertrude this whole time? Did Gertrude buy it? Was she convincing herself that Claudius hopped into Hamlet’s rightful throne out of love?
OR is Claudius trying out on Gertrude the rhetoric he’s planning on using on others later?