The Academy Awards are for "movies" that are to be projected onto a screen in a movie theatre. Netflix has chosen to not play by the rules that govern that way of distributing a film. There is no antitrust in this case. Now, if the MPAA made agreements with theatre operators to prevent Netflix from showing its movies in any movie theatre (which would then disqualify Netflix from being eligible for an Oscar), then that would be antitrust.

[Edited last sentence for further clarify.]