Safebooru is moderated by a team of people, each person has their own idea of what should and shouldn't be deleted. The ToS says "Only upload SFW (Safe for work) images. No porn or total nudity is allowed." Yuri should never be deleted unless it violates this rule. The act of two girls cuddling in a non-sexualized way is accepted on this site. It sounds like the image you're referring to was wrongly deleted. If an image gets deleted that you feel should not have been removed, feel free to make a thread and mention the link to the image and say why you feel the image should not have been deleted. It would be cool to see a general thread where anyone browsing the forum can post their concerns about specific images that are unjustly removed.
Also, you mention gore. Again, it's up to the individual mods that see these images whether it gets removed or not. Imo, as long as the image doesn't contain excessive sexual content, gore should be allowed. Whether gore is SFW is debatable. Maybe another mod that sees this can give their opinion.