I agree that adult content should be filtered out even when you're searching for specific tags - you should not have to know which terms are "all adult content" to keep them blocked. This is a bug that deliberately shows adult contents to people who have selected the "do not show me adult content" option, including minors.
Someone (not a minor) should do some research into what tags can bypass the "don't show me adult content" option. (If you search for ren'py, will you see adult ren'py games? Or is it only if you search the tags that definitely mean explicit sexual content? In which case... wow, that is a STUPID feature.)
If people want to see adult content and are dismayed when their searches for those tags come up blank, the page can have a message that says "You have this setting blocked in your profile options. To see these results, you will need to check the box that says..."
When I search on Steam, I often get results that say "4 titles have been excluded based on your preferences." (Or 12 titles. Or 37 titles. I have a lot of popular game tags blocked.) If I want to see those results, I can adjust my settings.