It seems like a stretch saying Deacon was closeted. I'd say it was pretty obvious to everyone he was gay. Even Walt would have realized it. Desi Arnaz hired Deacon to replace Roger C. Carmel on the second season of The Mothers-in-Law. Deacon played Kaye Ballard's husband and had no chemistry with her. But Deacon didn't make waves and he was someone they could count on to be professional and get the job done. Deacon had a long screen career because he was a team player and knew how to deliver a line to get laughs; his success had little to do with masking his sexual orientation.
Back then and stretching even further back to the 1920s and '30s, the popular catch phrase in Hollywood and Beverly Hills was "I don't care what you do behind closed doors as long as it doesn't frighten the horses". Somebody can correct me here on the exact wording.
Even though Washington D.C. was cracking down on gays working in government positions by 1953 (never mind what either Roy Cohn or J. Edgar Hoover did behind closed doors), all Hollywood was worried about were the tabloids. Yet there was so much "negotiating" with money involved, so it wasn't like you could NOT hide anything you wanted to a.k.a. Rock Hudson.
What happened in Tommy Kirk's case, I think, was that he was more open about being gay in 1965. That didn't please "Uncle" Walt. Ironically his most notorious film, Mars Needs Women (a non-Disney film he had to make later to make any kind of money) was filmed quickly the very week "Uncle" died (in December 1966). I think the title summed up the Disney/Tommy dilemma in a nutshell. Mars... and "Uncle" Walt... needed women more than Tommy did.
Tommy would be an entertaining guest to sit down with Ben. He could tell us the full story.
Going a bit off topic, I was watching an old documentary on Bewitched. The years just before and after Stonewall weren't all that bad if you were an actor/actress who could stay discrete. The long running joke is that you favor I Dream Of Jeannie over Bewitched only if you are strictly heterosexual with no "gay" sensibility and likely male due to all of the pre-Lib "yes master" talk. Don't get me wrong, I loved Larry Hagman and Barbara Eden. Yet you favor the other show because it was simply "fabulous" with its many colorful and, more often than not, closeted stars. Well... not Elizabeth Montgomery and the first Darrin, Dick York (father of too many kids to count). Agnes Moorehead was likely bisexual, since she was married for only a short time and had closer-than-close girlfriends. Many others like Dick Sargent, Maurice Evans and Paul Lynn certainly weren't into women at all and didn't even pretend to be. I personally favored Bewitched over Jeannie simply because it was so much funnier and creative.