Sometimes a new environment can be overwhelming, and if this was his first glimpse of the outdoors then it’s understandable if he was a bit on guard/nervous. He may have spotted a bird or another animal that frightened him, or he simply might have been overwhelmed by all the unfamiliar sounds and sights. Over time, as the environment outside becomes familiar, he should relax. As beardies mature they become a lot more easygoing and adaptable. My last baby was initially a neurotic mess whenever she was introduced to anything unfamiliar (a new room to explore, a new person, etc.). Now she’s quite the adventurer and she loves exploring new terrain or lounging outside on my lap when the circumstances allow. CooperDragon’s playpen suggestion can also help a skittish beardie enjoy some outdoor time while eliminating the fear that she’ll bolt/get lost. Just remember to always supervise any outdoor time. Hawks, snakes, coyotes, and cats will look at your beardie as a culinary offering, so depending on where you live, just make sure it’s secure from predators.
As for the coloring, even the normal/typical beardies found in pet stores can have little splashes of red, yellow, or orange in their coloration, so it sounds like Marbles just has a sassier pattern than his cohorts.
Maybe your friend would consider surrendering the beardie to a reptile rescue? He clearly doesn’t care about the animal’s well-being, and if it’s to the point where the beardie starves when he goes on vacation, then I don’t know why he’d insist on keeping this animal. Very few people are going to look at his setup/the way he cares for that animal and offer to buy it, for fear that they’re investing in an unhealthy pet with a questionable outcome. At least a reptile rescue can rehabilitate the beardie, give him proper UV lighting and the nutrition he needs, making adoption possible. It’s a really sad situation and I hope he can find it in himself to do what’s best for the animal if he has no intention of ever giving it the care it needs.
So otherwise Marbles seems to be doing well? Is he still a voracious little eater?
Also, you can always post some recent photos of Marbles and his new digs if you want some feedback on his coloration or his current setup.