What are you basing that on? The fact that he didn’t keep fighting? By that logic a champion is required to fight until they lose the belt in order to not be afraid, which is a pretty ridiculous standard.
The fact is despite how much you may dislike the decision GSP DID in fact beat Hendricks, who was the next champion after him. He also beat a guy who beat Lawler, the next champ after that, and he beat a guy who beat Woodley, the next champ after that, so you can’t really use the MMamath argument because it cuts against you harder than it supports you.
On top of that GSP was supposed to fight Woodley in his return. It was Woodleys lackluster performance against Maia which closed the door on that, so it doesn’t make any sense to say that GSP wanted nothing to do with the champs that came after him when he was lined up to fight one of them.
All that is to say, you’re certainly entitled to your opinion. I can respect the argument that GSP was boring during the latter portion of his title reign and that he played it safe and lacked a desire to finish.
As an example I personally found his fight with Shields to be exciting at the time because of the story around it and everything that it had taken to get there. Shields had been undefeated for about 6 years and was riding a 15 fight win streak that included names like Okami, Dan Henderson, Condit, and even a guy you claim GSP wanted nothing to do with in Lawler. He was easily the best WW outside of the UFC at the time and GSP had openly campaigned to get him there because he wanted to fight him. But without the backstory and an understanding of the stylistic matchup, it was boring as fuck. I wouldn’t show it to someone I was trying to get interested in the sport. So if you found it boring, I totally get it and I respect that point of view. But you’re stating opinions about his motivation that you can’t possibly know, and frankly struggle to support, and stating them as though they’re facts.