Oh, no worries at all! Your post doesn’t strike me as malicious at all. Just seems like we should be especially concerned with making the OPs feel “stupid” here :)
So it seems like you have 2 main points in your post (1 OP is overly worried, 2 sexual abuse is the real concern), so keeping both but with a more neutral tone:
You should not be worried about saying that a kid looks cute. The real concern that you’re hinting at with behavior toward children is anything that connotes sexual abuse, and the comment “that is a cute kid” is very different from that.
Or you could go for a positive tone:
You have nothing to worry about! Saying a kid looks cute is very different from sexualizing them.