I want to mount an AIO into a frame in a different orientation than the stack screw holes. Is using a TPU adapter with printed posts and press fitting in the AIO (no screw and no silicone gummy) a good or bad idea?

Crashes are violent. I cannot imagine that any kind of pressed fit will hold up.

Can you post a photo of what you described?

The post has a short screw on top to hold the VTX board so that gives some added rigidity, but the screw does not reach the FC. Just installed it, and too much torque screwing in the VTX screw snapped one post at the thin section so would probably need to reinforce that thin point. I was also worried if there would be too much wobble/vibration as that post can be forced up from the frame, the TPU mount is screwed down to the frame at the holes rotated 45 degrees.

That looks pretty secure and also give the FC a soft mount. I personally would try it.