Stern probably had a guard at the door inside the Dr's office who stopped Larry from going in while the swab was taken.
Then LB would go on to his appointment there and get *his* swab done.
Next would come court papers from HKS saying the Dannielynn swab wasn't taken properly because the opposing plaintiff didn't supervise the taking of it!
Howie wouldn't dare...
Can you imagine the media outside the mansion when Howie gets evicted?
He probably would've loved to block the door, but this DNA lab is very reputable and would not allow that imo.