Yes he will get credit where it is due.
So what that means is he will not get credit because none is due.
He was an employee of Mattel and his work was all work-made-for-hire.
He had no owenership. No ongoing rights. No claim of credit.
All of this would have been in the agreement he willingly signed in order to have his job.
Walt Disney is the creator of all the films that bear his name because he wrangled the artists, told them what he wanted, edited, changed, threw away, kept and produced.
And Mattel is the creator of He-Man.