gelbooru.com/index.php?page=post&s=view&id=2049118
In this post there are fully clothed Tenryuu and Admiral, but it's made clear that they are having sex (or rubbing their bodies together? idk), so it's labeled as explicit.

gelbooru.com/index.php?page=post&s=view&id=2019638
In this post they are in pretty much the same position, they are both bottomless, but they aren't having sex, so i's questionable.

Explicit is for any clear depiction of sexual interactions, sexual organs, or sexual fluids.

Safe is for images with absolutely no sexual content whatsoever. Tasteful swimsuit and innocent pantyshots as well as nudity that is clearly intended to be artistic rather than erotic are included here.

Questionable is for anything that doesn't exactly fit either of these two categories. It includes most nudity where genitalia is not depicted.

So if we take the peeing together while getting caught shot out of context from the whole image by itself it would become explicit.

Most likely yes, if it would appear that they're having sex.