Honestly...I was leaning towards ENTJ. The Te gives ENTJs and ESTJs often the same vibe. But the opposition to rules unless they make sense, while done by some ESTJs, tends to be a lot more noticeable in ENTJs, ime. ESTJs may not like when the rules are illogical, but they will do what they can to work within those rules and optimise their work logically within that framework, ime. They are more flexible on the rules than ISTJs though, and less fussy about the details. Disdain for tradition also smells of ENTJ, as they prefer to get things done regardless of how it was done in the past. Whereas an ESTJ, ime, is more likely to take the tradition and make it their own somehow (NeTe approach, as such).
Additionally, the bursts of silliness, being laid back, and the dealing with problems while being in the moment, smells like confidence in his Te and the use of his Se, especially when he is 'off the clock'. ENTJs on here/ventrillo for instance often display a fair amount of Se as well, as they are unwinding at this site, resulting in silly loud behaviour, creating fun drama and thinking on their feet when asked questions. My work colleague irl was like that as well. Though he took point with his Te, he actually was that good at his job that he would joke and be crazy in between, as long as it didnt mess with the workflow. Meanwhile, they will also engage their Se when something unexpected comes up at work, and are usually a bit more flexible on how to handle things as long as it works, compared to ESTJs. Ime (I had two ESTJ bosses in the past), ESTJs wait to clock out before they get silly, and take unexpected changes way more seriously, relating them back as fast as they can to the way things are done. They can definitely get inventive about how to get to the way things are done..but ultimately, thats where they end up
I also dont know what type you are, but if you are an N-dom yourself, then it is likely he is going to be less abstract than you and struggle more with it, in comparison, even as an ENTJ. I find that unless it has applicable value (Te), ENTjs tend not to focus on abstract things, and often when they do indulge in it, it is to serve that applicable value it could contain. Similarly, he might not be aware that he is using symbolism if he considers symbolism as a concept to be frilly and irrelevant to getting shit done. Asking an ENTJ to interpret a photograph is asking them to engage their baby Fi, and while some may relish in taking that challenge (especially those aware of wanting to develop that side of them), it goes against his typical nature: getting shit done. Interpreting a photograph just..might not be as rewarding and can seem frivolous compared to doing stuff that he can get tangible results from. If he is still quite young, this might be even more true, as he is still focused on his Te.
The game design major though...I found that interesting, as that does require a bit of vision. And imagination. Working out the practical elements is important to that vision though..which to me sounds NiSe.
*shrug*
Since I dont know him, and based on the information here, I can see both types. But I am definitely leaning towards ENTJ.