Was paralyzed on right side. Now he can use his arm and walk with walker almost cane. Should he stand for rehab?

I should add he did rehab hospital but had heart problems this year afib and chf.
But he had surgery and is in rhythum. He thinks because they had him at rehab lay down for exercise that it is best. I think he is strong now and needs to sit or stand to exercise. ANy advise thank you.