My kids wouldn’t mind because they would know that they weren’t actually pledging allegiance to a foreign power. But they would have my permission to refuse to participate if it did bother them.
Personally, If I had been in that position myself I would have recited the pledge but inserted the words “refuse to” into recitation just to mess with them.
Yet that is exactly what they would be doing. That's why it's called a pledge and not a "poem" or an "interesting factoid about wonderful mexico". Words have meaning.