Jurors previously heard Stewart, the 15-year-old and Turley were part of the Murray Boys gang from East Kilbride in South Lanarkshire.
Moy and his friends were stated to be from the rival Himshie group.
Findlay addressed the gang background but said being in a gang should not mean facing the consequences for a murder.
He told the jury that the Crown relied on Fraser Wallace – who was visited by the trio after the fatal stabbing – for their case but added the witness had lied “more than once”.
Findlay said the lies were “cold, calculated and despicable” and the jury should not let him “get away with it.”
He also claimed another witness wrongly told jurors Stewart was seen with a knife that day. The witness later admitted to reading this on social media.
Jurors previously heard Turley and the 15-year-old put up their hoods on arrival to Irvine by train.
But Findlay said Stewart did not do this as he had nothing to hide.
Findlay said his client was seen with an extendable baton at the beach because he was trying to look scary
And he added that did not mean he was looking to stab anyone.
The advocate told the jury his client did not know the extent of Moy’s stabbing and that he “celebrated” it.
He added: “The fact is he was behaving like an idiot afterwards…he was waving his baton around trying to look scary but I am not suggesting he is a nice young man or looking for approval or anything like that.
“He was not involved in the death of Kayden Moy.”