This is an excellent piece, and I heartily agree with all the sentiments contained here. Ageism is horrible and it creeps up on you gradually. For example, I've already experienced prejudice in this respect when applying for jobs, and I'm only 48.
On a related note, part of my vigorous recent defence of great film director Martin Scorsese is a response to "OK boomer" ageist nonsense being thrown in his direction by flippant nitwits on social media. Their philistine pig ignorance really, really pisses me off. This is Martin Scorsese, dammit. He knows a damn sight more about cinema than you do, has helmed several cinematic masterpieces (including his most recent film Killers of the Flower Moon, aged 80), and has done more for film preservation than you'll ever know. Show some bloody respect.