Nobody mistakenly walks into my house, the doors are not left unlocked. Therefore, if he got in, he broke in. Whether I've had a drink or not, under Florida's "castle doctrine", he's fair game.
Also consistent with Florida law, I must use the minimum force necessary to resolve the situation. The scenario says a he's a BG. How do I know? If he waves a weapon and shouts "gimme your money or I'll kill you", he just won a 9mm appendectomy. He's shown both capability and intent of inflicting injury or death.
If, however, he's empty-handed and shouts, "Where's that leaf blower I loaned you, Fred?" I'd have to point out that there are no Freds in the house and we have our own leaf blower, thank you very much. I'd still have him covered, and instruct him to leave or be hauled away by the Sheriff's deputies.