Alexei doesn't blame the receptionist too much for her mistake, if only because he knows her. He's had a few friendly (one-sided) chats with her and likes to think they're on good terms. Maybe she's even a Red Guardian fan! Who could blame her? So he stays ever pleasant, grinning even as she takes the suitcase behind the desk. And oblivious to how she struggles with the weight, of course. His attention goes right back to Bill himself.

"Oh, no! No minding! I will give you the tour," he says, slamming a hand down on the man's shoulder in a chummy manner. "Is there any location you would like to see first? Some of it is off-limits to non-Avengers, but I can try to sneak you in."

It should be clear right off the bat Alexei isn't the smartest bulb in the box, since he hasn't even asked for any kind of identification from Bill, let alone done some kind of test to make sure he's not looking at a Skrull.