This BBW mistress wanted to choke and shut up this guy at the same time so she used her big ass to do it. She did not care what he felt or whether he would shit himself. Her ass was sweaty and a little smelly but that did not bother her at all. In fact, it was an advantage and he had to lick her butt before she let him go.
This mistress wanted her butt worshipped and she knew her slave was the best bet for the job. She did not have to beg him and she knew he had to avoid pissing her off. She was also not sure whether she would like it and that is why she had him do it. Then if she loved it after he did it, she would open it up and have other guys do it as well.
Lady Alshari wanted to show this loser that she was not the sort of person to mess with. And that is why she chose to torture this loser and do it in a manner that he did not anticipate. She chose to use her hot ass to do it. He had to lick it and smell it the way she wanted and he was lucky she did not shit on him.