Responses

No the shards aren't safe for humans because of basically monsterfication of the person that's why he gave a bunch to his clones and they got red hulkfied
But even so it wasn't a new skill
Whatever mr mad scientist did actually broke the rule enough that if affected the main body to the point of he just manifested a new skill
Only a percentage of whatever is inflicted on the clone gets to MC right? I mean he used those broken potions and shards all the time on the clones and didn't get monster buffed skills