The DPAs have discretion on how they interpret the laws and what guidance they give. This is something you could only really pursue through litigation beyond what reply you're getting from your DPA. Personally, I am not trusting reddit to actually, truly delete anything. But there would need to be proof for that, beyond my suspicions.
If deleted was truly deleted, I'd say they're right on an individual case.
The issue I'm outlining is however of a different nature, so I am somewhat hopeful at least some DPA will take this issue on.