Is it valid for someone who catches the Imam in prostration and prostrates with him, then the Imam says the taslim, to stand up and pray the four rak'ahs of the Asr prayer, and what is the ruling on that in the Maliki madhhab and other madhahib?

If a worshiper catches the Imam prostrating in the last rak'ah of the 'Asr prayer, and makes the opening takbir while standing, then prostrates with him, and after the Imam says the taslim, he stands to complete his prayer, his action is valid according to the Malikis and others, due to the saying of the Prophet, peace and blessings be upon him: "When one of you comes to prayer and the Imam is in a certain state, let him do as the Imam does."

It has been stated in the fatwas of the Permanent Committee that whoever enters while the Imam is in the final tashahhud should join him for what remains. When the Imam says the taslim, he should stand and make up his prayer. However, what he caught of the prayer is not counted for him unless he caught a full rak'ah with the Imam.