Well, if that show was on air in 2019, it would be. The Mr. Roper character, Jack’s landlord, was always saying and doing things that were stereotypical/derogatory towards gay people. The characterizations and references to gay people would most assuredly not have been anything any series now would dare to include as part of the acting or writing or character development.
But for the time it was on air, it was actually pretty ahead of its time. In the late ‘70s-early 80’s, gay characters on TV were pretty much nonexistent. Soap was the only other show at the time that had a gay character on it. Other shows during the time barely acknowledged gay people, let alone bisexual or transgendered people and when they did, it was for laughs. While Jack was not gay, the series revolves around him pretending to be gay to his landlord in order to be able to share an apartment with two women. To the landlord, Jack was an openly gay man. Gay people during the time this show aired for the most part were still deep in the closet even in places like California, and those who weren’t found life unpleasant.
During the time period the series was on air, openly gay people (which Jack was as far as Mr. Roper was concerned) would have had problems even finding a place to live. Even straight couples who weren’t married or couples with children would have had problems finding rentals—-landlords had far more leeway to deny housing to people during that time. That Jack was allowed to rent an apartment as an openly gay man living with two women was a fantasy in the 70s, even in California—Mr. Roper was a man in his 60s at a minimum at the time, and thus would not have been the most progressive minded person. The vast majority were also not out to friends and family like Jack was—there were very few places in America where an openly gay man could go without enduring major hassles or abuse.
So, for the time, it was not insensitive. It reflected the times, and in some ways by acknowledging the gay community even existed by making a character “gay” for its premise and having that character not be subject to abuse or crippling discrimination by people who thought he was, the show was more progressive than most of the shows on air at the time.