Just curious, why do you want to remove the dry hop but continue conditioning the beer? If you give the carboy a tiny tiny shake each day during the dry hop, it will all drop out. Now you're not risking contamination from the bag that has a ton of spaces to harbor nasties. If I used a muslin bag, I'd boil it first then hit it with a quick star san bath then into the fermentor to be extra safe.
You could also cold crash with the loose dry hop. Stick the carboy in a bucket of >50° water for say 8 hours and you'll drop a lot of yeast and all of the hops to the bottom then rack into keg or bottling bucket.