Assuming you are talking about me, I've not criticised you, just tried to tell you that these things are completely irrelevant and can often be misleading. That is certainly the case with Thorn, which has no more problems with low notes than it does with high notes, yet you've convinced yourself it has because you look at things that don't matter. It's perfectly fine to say "isn't that interesting" but when you look at the results and say "so I'd never use this synth for xxxxx", you are doing yourself a disservice.
In this instance, I imagine the roll-off is possibly to reduce/remove aliasing but I'd be very surprised if you could hear the effect of it when you are playing the instrument or making patches for it. So yeah, interesting but irrelevant.