All the people saying don't use it are welcome to send me their carbon parts with minor cosmetic damage.

This looks exactly the same as the "printing" I've gotten on every single pair of carbon bars I've used at the clamping point. I haven't seen it on my carbon seat posts though.

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So long, and thanks for all the fish.

While I wouldn't care to take a chance with my "undercarriage" in case the SP should break, since you asked have you tried tapping the post there with a metalic object at the area in question and elsewhere to listen for differences in sound that might suggest the area in question is "soft"??

If you do plan on using it, I'd still sand down the gouge as to remove any possibility of a stress riser there. Also, I would round off the edges of the seat tube split and the top edge as well. Emery cloth or jeweler's files work well for this.

+1

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My Renovo R1 wooden bike project

Check it out: the most amazing vintage Colnago, Merckx and Pinarello collection

I fixed one of my pupil's posts that was like this. Looked exactly the same from the outside.
Simple test:
Get a bright light and look at it inside. Any deviation inside at the same place means it's failed. If the wall over that zone is uniform inside it's probably fine.
My pupil's one had a small deviation so I knew the tube had started to fail. I roughened the inner surface and epoxied a reasonably thick UD patch over the zone and pressurized it into place using an old bike tube and many layers of cellotape as a make-shift bladder. Worked a treat. The "dimple" that remained on the exterior was filled using epoxy resin then sanded flat and given a couple of coats of clear. You couldn't tell it had ever been touched and the deformation never recurred. It lasted for ages and was still functional when he replaced the pillar with a longer one.

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Used to race....got too wrinkly and old Updated: Racing again! Thought this was unlikely! Eventually, I may even have a decent race!