Why is riot keeping aatrox gutted

They're planning on giving him some changes during the Diver class update, which will likely be the midseason 7 update.

As for "Jax and Tryndamere doing the same job," there's a real big thing that Aatrox has that they don't: large amounts of inbuilt sustain. Aatrox's W allowed him, on release, to basically fight anyone at any time just by right clicking them to death and, even under turret, come out of it full health. He's staying gutted until the class update where they'll try some decently sized fixes for him because if he's allowed to be strong he becomes cancer.

Release Aatrox was a cancer that could sustain through anything and be tankyaf. He was unkillable literally.... Shudders

They're supposed to do a mini-rework of him real soon. (Shyvana-scale)

Because jax and trydamere don't have built in sustain to the level that aatrox has. I've faced good Aatrox's, there is no coming back in lane against him if he is good(or strong)(this was pre executioners though so im not sure how it would go now).

they should move that sustain to different power and get rid of that second life