that's the point, they're not superhumans yet , Tanos said that what remains of their bodies at been found and he have to adminster the serum just before their ascension to establish the connection , and they have technology to keep them alive even in that state
That's assuming that Tanos was telling the truth to Deryl. He also mentions how superhuman bodies are incredible while he was dissecting Amber, which implies that she's already changed.
I can see it going either way, that he was telling the truth and that he's dissecting the twins while they're changing, or that everything he told Deryl was a lie, and he's going to dissect the twins to study their power, and likely plans on doing the same to Deryl when he's done. He could have encouraged Deryl to make a new philosopher's stone so that he could take that and use it to improve his own power.
I don't think his plans are going to matter in the end, because it's likely Deryl is going to invent something that will help him try to rescue his friends, and soon after the MC finishes his dream journey and comes out to help.
It'll be interesting to see how the MC will deal with Shen afterwards. He's learned that if he adds additional people's memories to the dreams that it interferes with Shen's power. He should be able to shrug off Shen's power afterwards when combined with his own skill with his Memory power getting stronger, but Shen is still a 4th level Superhuman and should have a physical advantage over the MC just based on raw power levels.
Edit: I'll add this here rather than starting a new post.
I just realized, H.E.R.O. had to turn down their power containment fields in order to store Eisheth. It's a shame that they likely diverted most of the power from the cell containing Ella's dead body. There's no way that could possibly go wrong for them.