No, that isn't the case, carmen. In fact, the opposite can happen where a frail and elderly person is 'coerced' into complex tests and treatments, some of which can have the effect of shortening life. HCPs are in a difficult situation. Now laws have been passed saying that you cannot discriminate on the grounds of age, with a shrug, 90 year olds have to undergo colonoscopies (along with the days of diet and prep that involves), barium enemas, aggressive chemotherapy regimes. They do it so relatives cannot sue them for discriminating against grandad because he was old, so he is 'treated' like a bloke half his age.
I obviously wouldn't seek to comment about your poor FIL's precise situation, but I have to say that, on a daily basis, I see very elderly people undergoing diagnostic tests that will in no way alter the course of their condition, but, imo, could even hasten the end as the tests are so physically demanding, confusing, put a lot of strain on elderly bodies and sometimes are painful for the patient concerned- and, again, imo, are tantamount to elder abuse, to be honest!