YOU SAID:

He won't be able to walk by without stopping to urinate.

INTO JAPANESE

彼は小便に立ち寄らないと歩けないだろう。

BACK INTO ENGLISH

He won't be able to walk until he stops for a piss.

INTO JAPANESE

彼は小便のために立ち止まるまで歩けないだろう。

BACK INTO ENGLISH

He won't be able to walk until he stops for a piss.