For you guys that are wondering, yes, this is the same Rockwell from the explorer notes. He injected himself with liquid element after becoming obsessed with element, and transformed into the hideous thing he is now.
To be honest I believe that the reason Rockwell injected element into himself was because he was scared and paranoid that other scientists like Helena and wanted to prove himself better it's kinda sad either way
Considering he’s a boss, there’s not much utility to him, other than getting bonus levels from Aberrant Ascensions.
Though if you think about it, Rockwell (before at least) had a ton of utility. He made all of the cooking recipes (as suggested by the Rockwell notes that are somehow everywhere), and it’s heavily implied that he made a good portion of the technology available to you in Aberration.
Still, what a sad and twisted way to go for probably my favourite character in all of ARK: Survival Evolved’s storyline.