I did have an umpire tell me once that if another of my 8U players ran with less than two outs and first occupied on a DTS that she would eject me for "making a mockery (sp) of the game".
Whenever an umpire tells you that he's going to invoke some mysterious "mockery of the game" rule, he's just making stuff up.
There isn't any universal, all-encompasing "mockery rule" that an umpire can pull out to cover any situation he just doesn't happen to like, or anything possible situation that seems unusual or out of the norm.
Whatever the player is doing is either legal or illegal. There is either a rule that covers it or there isn't. And, in this case, there is a rule and here is what it says (paraphrasing a bit, to cover multiple rule sets):
A runner is out when...After being declared out or after scoring, a runner interferes with a
defensive player's opportunity to make a play on another runner. A runner
continuing to run and drawing a throw may be considered a form of interference.
NOTE: This does not apply to the batter-runner running on the dropped third strike
rule.
The rule specifically makes an exception for a retired batter taking off to first base. Running to first, when you're not allowed to, is not in and of itself illegal or a form of interference. It can becopme interference, if the retired batter in some way actually interferes with anothr play on a viable runner (for example, if there's a runner on first, the catcher tries to pick her off, but the throw hits the retired batter).
Any umpire who threatens to eject or penalize a retired batter for running to first base when she not entitled to, under some imaginary "mockery of the game" rule, is making a mockery of the game!