What issue of concern was there for Charlie once he returned to the lab?

Charlie's issue of concern was what would happen to him if the experiment wasn't successful. He wanted to know what plans we made for him if he regressed..... if things turned out to only be temporary. Charlie was concerned about his future and told Nemur he had the right to know.

"Tell me," I asked Nemur, "I just got a look at your incinerator for disposing of experimental animals. What plans have been made for me?"

My question stunned him. "What do you mean?"

"I'm sure that from the beginning you planned for all exigencies. So what happens to me?"

When he was silent I insisted: "I have a right to know everything that pertains to the experiment, and that includes my future."