Is an MRI test harmfull for his age?

Why MRI, there must be reason for investigation other wise wastage of money. By the way MRI with out contrast is not harmful but with contrast they check the kidney function, because they inject a dye and kidney has to expel that from body. First consult your GP then specialist and when specialist recommends that get MRI.

Does the doctor think an MRI would help with the diagnosis? Has the doctor suggested seeing a specialist about the weakness?

When an elderly person has an operation it would not be unexpected to take longer to recover to the former level of activity. But it shouldn't take from March to December, so I would continue to pursue a medical diagnosis and treatment plan.

His doctor is unable to diagnose the symptoms for his weakness and I thought may be MRI scan will show us any results for his daily challenges to move around. Most of the family friends are suggesting that he is old and had an operation and that's why he has difficulties to walk

I have never heard that age is a factor for MRI testing. Perhaps someone with medical training will answer this.

Does a doctor want your father to have an MRI? Or are you concerned about one he had in the past?