Obviously, the left has already made clear that pedophilia is okay, if done by their own. BLM organizer, Christopher DeVries arrested on six counts of possession of child sex abuse images. There is a growing conviction, notably in Canada and California, that paedophilia should probably be classified as a distinct sexual orientation, like heterosexuality or homosexuality. Two eminent researchers testified to that effect to a Canadian parliamentary commission last year, and the Harvard Mental Health Letter of July 2010 stated baldly that paedophilia “is a sexual orientation” and therefore “unlikely to change”. Or these disgusting pedophiles think they are "oppressed" https://aboutpedophilia.com/tag/blm/
On topic:
10 years gap is way too much, that is obviously protecting and normalizing pedophiles, given the age of consent is 18 in California, the difference would thus mean an 8 year old child.
The "worst case scenario" is 17 with a 27 year old - clearly the age gap means that the older person is much more mentally developed than ANY 17 year old. If you are trying to protect the age differences, I'd say 3-5 years, that gives a 17 year old sway with up to 22 year olds.
It is scientifically accepted that most people's prefrontal cortex will not be fully developed until 21 anyway, so you could argue that the "impulse control wasn't fully developed yet". Worst case is an 18 year old high schooler with a 13 year old, some 13 year olds are notoriously adult. Anything that protects sex with younger than 13 is pedophilia normalization, something that has held for thousands of years, all societies have protected their young up until the age of ~12-14yo.
There is no sub-12yo that is sexually developed, most people become there around 16 and that was the lower average age range throughout human history, sure there were places where taking younger females (not males) was allowable but it was virtually never fully acceptable and was more about legally protecting the proclivities of pedophilia within the aristocracy.
With a 23-27 year old that argument no longer holds, you can drink, you can choose not to have sex with a 17 year old.