Thanks for the fic link, Prissy!
I understand how one can interpret Red as having love for all the kids.
My personal opinion is that, especially after season 1 -- though he cared about them -- he didn't love Kelso, Fez, or Jackie. But had Red maintained his more complex characterization of the first season, we might've gotten scenes where Red's relationships with Kelso, Jackie, and Fez were developed more positively. I would've liked to see that.