He's been living in the US for 16 years, so thats not a valid excuse. Also, there's a difference between not saying please and being vulgar. I don't think you can dismiss this as merely a cultural issue.
Not a valid excuse for what? Who said he has to be "excused"? To quote George Bernard Shaw, who told you the customs of your tribe in the US are natural laws?
>* Also, there's a difference between not saying please and being vulgar.*
As there is a difference between swearing and being vulgar.
And besides, it's not exclusively american people he deals with. He probably gets along fine with e.g. Russians who have a culture that is more similar to his own.