You did no wrong. You did right. For any JW to expect you to break the law - especially one which involves the safety of children should fall into the territory of council from the elders (not obeying supperior authorities, holding life sacred, stumbling others - etc).
Someone I knew was convicted (wrongly) of driving without due care and attention (they were in a crash with a very old lady who survived - but only just) and despite a jury twice not reaching a decision the elders took him off as a MS and put him under restrictions. Did he cause the accident? no - he actually took evasive action - but the elders acted as it had been notorius. I wonder who the elders would have pointed the finger at if you'd been in an accident and one of the children were hurt.
I think the generation thing is a factor. My dad often skimps on safety because "that's what they used to do in his day".
In my own experience I've found many JW's cherry pick what legal rules they follow or not - more often to do with how others in the cong will view them rather than what Jah would think or indeed what is actually legal/right!
MMXIV