Have two older gay friends "into their 50s and 60s". One of them is defo a bottom and has no problems at all. You can get incontinence from repetitive injuries to your sphincter muscles, that is if someone is trying to penetrate you while they are clenched. If you bleed or feel acute pain every time you are having sex then you are doing it wrong and, yes, you are running the risk of getting injured which, over time, might lead to continence problems. But, as far as I have heard and read, anal sex done safely, with abundant lubricant should not cause you any trouble.
Of course I would say maybe do it moderately? For example, if you and your bf have a very high sex drive and can afford to have sex a few times a day (some couples do) perhaps limit the anal sex to once a day, or even once every other day? That's entirely my opinion and what I would do, some people might disagree.
Personally I wouldn't have anal sex with my bf more than once a day and, to be honest, I wouldn't mind if it only happened a few times a week as opposed to every day (I am a top), because there's also other ways to enjoy sexual intimacy with your partner, and I think gay couples perhaps tend to be more inventive anyway, because anal sex is not as practical and easy to get as vaginal sex, so you gotta learn to enjoy "other stuff too".