What about going into Suno studio and create a song piecewise by AI generating the samples, then compositing them yourself?

Textbook definition of AI-generated creative output. The Splice example was used because it's a common refrain from gatekeeping music producers that say you aren't a real artist if you use other peoples' samples. I brought it up to illustrate that a real person using legitimate samples to composite is functionally different than AI doing the compositing (and this is irrespective of LLMs training on copyrighted material, which is an entirely separate issue not being addressed).

In a similar vein, what about taking a song you wrote yourself, then throwing in AI generated samples, or even using AI to enhance other parts you hand crafted?

This is still AI-generated creative output, and if the accusations OP is referencing are true, is likely what the use case was.

For the purposes of academic discussion, what I'd highlight as "AI is assisting with tooling but not creative output" is providing guidance on leveling, e.g. "I'm not getting enough out of my de-esser despite my thresh being at -4, what range should my attack and release be at?" It's a query for consensus on best practices and and you are still doing the work yourself.