Radiation for 70 yr old (glioblastomas grade 4)?

Good afternoon,
A friend of mine learned that her dad was diagnosed with glioblastomas (grade 4.) He is 70 years old. He did the surgery and the surgeon asked the family whether to proceed with the chemo and radiation.
At this moment, he can barely walk.
The radiation will be around 8 weeks and we were wondering what would be the benefit of it. Reading articles, it seems that for his age, the gain would be marginal and if it is to gain 3 months more but 2 of them (at the start) are lost in daily radiation at the hospital, is it worth it?
Also, we were wondering as one of the potential benefit would be an health improvement (after some potential difficult moment during the chemo) but we could not find whether or not it would be the case?
Finally, is there any benefit in doing only chemo (which consist in daily pills but can be done at home hence less demanding)?
Did anyone had this dilemma and what was their choice/guidance? Any (recent) article/research paper?
For me it seems the most important question instead of increasing the life expectancy, is the state he will be in during/after the treatment.

Thanks for reading and any help would be more than welcome in this difficult moment