I'm on the side of no on this.
While you can find horses of that age that are still riding? You can also find nice calm horses of 5/6/7 that you would have many years with.
And unless you have unlimited funds you could well spend your money taking care of horse that has too many issues to ride safely, if at all at that age.
I also know from my aging body that things wear out and horses are more stoic about pain, discomfort than we are.
I bought my QH at 5. He has not ever put a foot wrong, (other than wanting to take off on daughter) so I took him over. He was not bolting, just cantering back to fence. Had she come back on reins, he would have responded and stopped his foolishness. I got her another horse, one that was dead head.
He is now 19 years old. Sound. And he is the same horse under saddle every time, whether he is ridden daily, or not for couple of years. Just that type horse.
To me, you would get more out of horse that is 6ish and up, than you will get out of one this old.
Horses make me a better person.