Interesting to know there is flexibility then, if the airline doesn't notice (which isn't that likely I feel, but clearly worked for DH188, unless it was land borders you were crossing?).

I would just say the following based on my risk appetite:

1. Traveling for a leisure trip, with children, knowing there is a risk of deportation sounds like a fairly extreme step for presumably some, but few benefits. I guess there my be a reduced chance that the country would deport your child only, but all it takes is one person following the (clearly stated) rules and it is trouble, and would they deport the whole family, or just one parent and one kid? Seeing another part of Bali (or Indonesia, or Hong Kong) for the time spent in Thailand would give a few fun memories I am sure.
2. If you have ever been deported from another country for any reason, this normally blocks off visa-free travel for many countries (at least for a number of years) and can come up in other visa situations. I would not want that on my kid's record.