Background: Lenny Bruce was born Leonard Alfred Schneider to a Jewish family in Mineola, New York, grew up in nearby Bellmore, and attended Wellington C. Mepham High School. His parents divorced when he was five years old (the documentary Lenny Bruce: Swear to Tell the Truth claims he was eight years old), and Lenny lived with various relatives over the next decade. His British-born father, Myron (Mickey) Schneider, was a shoe clerk and Lenny saw him very infrequently.
Context: On October 4, 1961, Bruce was arrested for obscenity at the Jazz Workshop in San Francisco; he had used the word cocksucker and riffed that "to is a preposition, come is a verb", that the sexual context of come is so common that it bears no weight, and that if someone hearing it becomes upset, he "probably can't come". Although the jury acquitted him, other law enforcement agencies began monitoring his appearances, resulting in frequent arrests under charges of obscenity.  Bruce was arrested again in 1961, in Philadelphia, for drug possession and again in Los Angeles, two years later. The Los Angeles arrest took place in then-unincorporated West Hollywood, and the arresting officer was a young deputy named Sherman Block, who later became County Sheriff. The specification this time was that the comedian had used the word schmuck, an insulting Yiddish term that is an obscene term for penis. The Hollywood charges were later dismissed.  On December 5, 1962, Bruce was arrested on stage at the legendary Gate of Horn folk club in Chicago. The same year he played at Peter Cook's The Establishment club in London, and in April the next year he was barred from entering England by the Home Office as an "undesirable alien".  In April 1964, he appeared twice at the Cafe Au Go Go in Greenwich Village, with undercover police detectives in the audience. He was arrested along with the club owners, Howard and Elly Solomon, who were arrested for allowing an obscene performance to take place. On both occasions, he was arrested after leaving the stage, the complaints again pertaining to his use of various obscenities.  A three-judge panel presided over his widely publicized six-month trial, prosecuted by Manhattan Assistant D.A. Richard Kuh, with Ephraim London and Martin Garbus as the defense attorneys. Bruce and club owner Howard Solomon were both found guilty of obscenity on November 4, 1964. The conviction was announced despite positive testimony and petitions of support from - among other artists, writers and educators - Woody Allen, Bob Dylan, Jules Feiffer, Allen Ginsberg, Norman Mailer, William Styron, and James Baldwin, and Manhattan journalist and television personality Dorothy Kilgallen and sociologist Herbert Gans. Bruce was sentenced on December 21, 1964 to four months in a workhouse; he was set free on bail during the appeals process and died before the appeal was decided. Solomon later saw his conviction overturned; Bruce, who died before the decision, never had his conviction stricken. Bruce later received a full posthumous gubernatorial pardon.
Question: Why was he considered to be an "undesirable alien"?. Whats the answer?
On December 5, 1962, Bruce was arrested on stage at the legendary Gate of Horn folk club in Chicago.