I say, with Allah's guidance: If a junub performs tayammum and intends it for wudu, it is sufficient and his prayer is valid, and he does not need to perform tayammum for janabah. If he performs tayammum for wudu and intends janabah, it is permissible; because it is valid for a junub to perform tayammum with the intention of wudu, and this is the ruling given. It is not required to intend tayammum for the minor or major ritual impurity according to the correct view. Refer to: Al-Durr Al-Mukhtar 1: 165, Radd Al-Muhtar 1: 165, and Al-Idah Q6/b. And Allah knows best.