Horseshoe crabs are not crusteceans, they are early chelicerates.
They have an open circulatory system, where the blood (heamolymph) freely spills out of the arteries into surrounding tissues, so a small clot probably wouldn't cause issues. Think of it like a cyst, sometimes if an infection can't be removed by the immune system, your body will just enclose it in a capsule, so it can't spread.
Yeah, I may be a bit combative in my comments, but in general I dont want to contribute to toxicity, so when I'm wrong I'll fess up and apologize for it
I feel you and I don’t know your age but me personally I found that with age, I was more forthcoming with saying i was wrong and just trying to be nice to folk.
Age might play a part in it, I do think I've been more willing to fess up to wrongdoing than average throughout my life as well though as I function best in honest environments. You have a great day as well!