LHO was involved? Absolutely.... He was the patsy....
That's not what Garrison alleged in the Clay Shaw trial which is what the topic is about, i.e., Garrison's behavior in the Shaw matter and his repeated abuses of the law in the investigation he conducted. He smeared and ruined numerous people's lives. Based on little more than his own, sometimes sordid, fantasies; although he probably believed most of them.
Garrison said that Oswald conspired with Shaw and Ferrie and others (unnamed) to shoot the president. And that Oswald was the one who brought the murder weapon - or one of them - to the TSBD. Garrison said explicitly that Oswald was a willing and active conspirator in the murder of JFK and not a patsy.
This is from his opening statement to the jury in the trial:
"The defendant, CLAY L, SHAW, is charged in a bill of indictment with having willfully and unlawfully conspired with DAVID W, FERRIE, LEE HARVEY OSWALD and others to murder JOHN F. KENNEDY."
Again, Oswald was one of the conspirators in the murder of JFK. Not a patsy.
This conspiracy involved: "Discussion by OSWALD, FERRIE and the defendant, SHAW of means and methods of execution of the conspiracy with regard to assassination of JOHN F. KENNEDY -- particularly, the selection and use of rifles to be fired from multiple directions simultaneously to produce a triangulation of crossfire, establishing and selecting the means and routes of escape from the assassination scene, determination of procedures and the places to be used for some of the principals to the conspiracy so as to establish alibis on the date of the assassination."
And the conspiracy also included: "LEE HARVEY OSWALD taking a rifle to the Texas Book Depository in Dallas, Texas on or before November 22, 1963."
So Oswald discussed and planned out the murder of JFK. And brought a rifle to be used as part of that act. If Garrison was right then your theory as to what happened is 100% wrong.
Garrison's full opening statement is here:
https://jfk-online.com/state.html