Blowing your nose at the table is not allowed at all. Excuse yourself to the table, go into the restroom, blow your nose, wash your hands, and return. It is one of the single most complaints I receive from my readers regarding manners at the table. It’s rude and can make even the most savory meal suddenly unappetizing.
Then be prepared to watch my nose drip right into my food. Sometimes you gotta brake the rules.
Nose “tapping” is fine. Nose blowing is not.