You don't see any LGBT overtones in the original books because it takes place in the 90's and it is a children's book series about a magical boarding school. If the absence of LGBT overtones, in that context, is "shocking, conservative and traditional" then you have a low bar.
Taking away Muggleborns' wands only makes sense as an allegory for gun control if wands were only used as weapons, but they are used for all kinds of magic, beyond self-defense. In order to be an equal participant in the Wizarding World, you need a wand. Taking away a Muggleborns' wand was Death Eaters sending the message that they were not equal.
Furthermore, there is plenty of restrictions on wand usage in the Harry Potter books. Goblins, house elves, etc. are not allowed to own wands. Students who are expelled from Hogwarts (Hagrid, for example) are not allowed to own wands. And each wizard is only allowed one wand. You are not allowed to stockpile them, the way that American gun enthusiasts tend to do. The reason that J.K. Rowling did not bog down her books with legal theory on when someone is or isn't allowed to use magic is because her primary audience, adolescent girls, would get bored.
The "traditionalist" character, Salazar Slytherin, is portrayed as evil and backwards. There is a wide variety of female characters and witches are not confined to "traditional" gender roles. The series celebrates and promotes diversity at every turn.
Harry Potter is a book series built on liberal value and anyone who argues otherwise is in denial.