General Anaesthetics are a last resort, it has small but significant risks. I can understand a clinician making  a decision that some teeth that might be filled in the short term would not last up to eight years before the permanent succesor comes in. The last thing anyone wants is to have to return in a couple of years for the another GA.
THe issue is consent , I expect that the some filled some taken out allows latitude to investigate on the day and act appropriately. In this case it appears that the findings were all unfavourable, which is not the average but does happen.
If you have an issue you could take it up with the hospital.
9 teeth requiring extraction at four ( some teeth have only been around in the av mouth for 18 months) means very high decay rates.
1.  Check for weak enamel type issues
2.  Restrict snacking and juice drinks between meals, Diet control is the best weapon we have to control decay.
Rob