MOO: I find it odd as well, but the family have declined to release one.
I assume it's because they're living SO remotely, so the public don't really need to know what he looks like as they wouldn't be able to do anything anyway - Yunta is a very remote, very small town. Maybe there's photos going around Yunta?
They also took a day or two to release Gus' surname, but none of the other family members have been named.
I'm guessing there's enough evidence to show that Gus genuinely got lost on the property but personally, I wouldn't be ruling out other possibilities. I'd be putting out as much information as I possibly could in the unlikely scenario that someone took him.
Other Sleuthers have also speculated that he, and/or other family members may have their personal details protected for legal reasons (eg. unrelated family court rulings, fostering etc.)
MOO.

I keep searching for updates hoping that they've found him alive and safe. This is such a heartbreaking case. I hope the family has an abundance of support and comfort right now. I can't even being to imagine what they must be going through right now