Thank you GreenWhiteBlue.Both are incorrect. A job is not busy, although it may cause a person to be busy. "Working intensive", though, is simply not English. Also note that (in American English at least) "restroom" is a term for the room where one finds toilets and sinks, and such rooms are not used for resting in the ordinary sense of the word.
Thank you Myrmidon.Your second sentence is the same as "He uses the restroom and gets no time to rest." The negative doesn't apply to "uses the restroom" so it seems he poops and pees a lot.
He is very busy at work / at his job. He gets no time to rest or use the restroom.
Now he can't poop or pee at all which is a problem.