I have interviewed and hired older workers and have worked with older workers in all of my previous companies. Age discriminatin is a real thing, and yet
someone hired those older workers, so it's not an insurmountable thing. You often hear things like "well, you need to keep constantly learning new things", which is true, but older workers don't need to pretend to be younger workers as they have their own advantages and disadvantages, and are better off pushing their advantages than insisting they don't have disadvantages. The advantages of older workers are:
* better judgement, more emotionally mature, more likely to see projects through to completion, more likely to stay at the firm longer. Play up to the advantages. Assuming these are, in fact, actual advantages of this person.