No. Jimmy's whole life has been about fast talking, charming and scamming his way through life no matter who got hurt. Some of it out of spite or twisted fun. Scammed his father, pushed Chuck into killing himself with the insurance cancellation. Helped get a murdering cartel boss out of jail, destroyed Howard's reputation before indirectly getting him killed. Helped run one of the most biggest drug operations ever. Scammed people through identity fraud for no reason other than he was bored, including a man that had cancer. Not to mention all of the other schemes and scams he has ran over the decades.
With the confession he stopped running, stopped scamming and took full responsibility for his actions, something he has never done before. This was most likely his first time he did not try to weasel out of his shenanigans and actually told the truth, knowing doing so he was going away for good.
What was he supposed to do? Blow up the trial? Work some last minute magic and get probation for all of the crimes he was charged with? He was a man on the run with his past actions hanging over his head and he received some measure of relief by owning up to what he has done.
No more sleazy ambulance chasing Saul Goodman. No more scamming and fast talking Slippin' Jimmy, just Jimmy Mc'Gill.