YANBU for wanting your DS to have his friends over. I know exactly what you mean about wanting to be the home that the DC come to. My parents were very much the same: friends welcome over (some had very difficult/challenging home life), they did have house rules, and wouldn't hesitate to remind our (me/my siblings) friends to tidy/clean up after themselves etc. My parents wanted our house to be a safe place for us/our friends to hang out in (far better that than us hanging out on the streets). They even took in one of my brother's friends when his mum had a nervous breakdown. When me/my siblings left home, our friends would still drop by to see my folks. When my folks died, the Church was packed with not just family or friends of family, but our own mates who adored my parents and wanted to pay their respects. And yes, my parents were strict with curfews, behaviour etc.
I've kept the same thing going with my own DC (they're now 12 and 19): my house is SMALL (and only one bathroom!), but we budge up and make room and friends are welcome over. I know they're all safe, and I can keep an eye on them. Yes, teenagers are like locusts, but I make sure snacks/soft drinks available, and we have plenty of camping beds/mattresses for DC's friends to sleep on. I have house rules (clean up after yourselves!), and expect good manners, homework to be done etc, but they know they can come here and I'll make sure they're all safe. I'm apparently the first port of call if eldest (DS) has been on a night out and one of his group is stranded/can't get home (particularly when they were all still in 6th form). Far better they come to my place, where they'll be safe. My eldest is away at his Dad's place at the moment, but one of his friends (who he's known since they were 4!) swung by to say hello this evening (and asked to use my treadmill!!). He had supper with me/my DD (there was plenty to go around), then helped with the washing up before heading home. 😂
If your DH has an OCD diagnosis, then I can't imagine how difficult it must be for him. It would be good for him to get the help he needs to manage his condition better, but this shouldn't prevent your DC having friends over.