Might-Makes-Right alert.
An honest man would answer the question. Are you honest?
Now put yourself in the sheriff's shoes: the law says you need to go there, and the resident has threatened violence. So what do you do?
Just about anything but stage an armed raid into the house, or trailer as it appears is the case here.
Good alternatives would include negotiation with the parents, finding someone they trust to mediate the discussion, finding a nurse/doctor/EMT they trust to look at the kid at their home, etc.
Staging an armed raid is just plain stupid if there really was any risk of the parent responding violently. Who would think that risking a close quarters firefight with an 11 year old in the middle of it was a good idea in order to take the child to the hospital for an X-Ray? Either the sheriff knew that violence was unlikely, and just wanted to show off his SWAT team, or his judgement is sorely lacking.
A forced entry into a trailer is particularly dangerous. Think about the layout of a house trailer, where the door is on the side, and partitioned areas are to the left and right of the door. Upon entry you have to immediately turn left or right. The door partially blocks your sight line to the left. None of the partitions, or even the outer walls will stop a projectile. So every bullet fired goes right through the structure and continues outside. For 9mm and above, the rounds passing through the trailer still have lethal velocity.
Had the father been a real nutcase, the SWAT team would have faced fire from the side, with a poor to non-existent sight line, and only their body armor to rely on for protection from the fire. Team members outside of the door would also have been hit, since you can fire right through the walls of the trailer.
Return fire from the SWAT team would have presented a grave risk of injury or death to the 11 year old.
Regardless of how anybody feels about the necessity of examining the child, or the mindset of the parent, the sheriff's decision to use a forced entry was a huge mistake.