According to their website, no.
All our varieties are bred using classic and traditional seed breeding techniques without any genetic modification (non-GMO).
"is it legal to use biological waste after consuming those peppers?"
I do not understand this question.
"is is healthy?"
To quote Bill Clinton: "it depends on what the meaning of ‘is’ is"
https://piped.video/watch?v=DmVkkkuZLeU The music video makes it even better. But may trigger epilepsy.