There are better choices, but they cost slightly more I guess. Its pretty hard to get good tones out of the Spider3  unless you spend hours on it. I'm no fan of it so I can't say much other than recommending you away from it.
And of what significance branding does to a guitars playability and tone? Sure, Gibson, PRS, ESP, Fender are "branded" because they produce stellar guitars, sure but for how much? You pay for what you get. Those brands use premium grade wood with strict quality control. If you're gonna recommend him to get a "better" guitar, you're probably going to tell a student who isn't making much even with part time jobs to get a probably 3000MYR and above guitar.

First thing first, are you skilled enough to own a "better" guitar, if your fingers can't keep up with your guitar, it doesn't matter if its a relic '59 Les Paul into a 87 JCM800 with a boat load of pedals, you're still gonna sound bad.

If you think installing pickups into an SX or a cheap guitar is not going to affect tone much, rest assured, many can prove you wrong easily. Cheap guitars come with poorly made pickups, meaning they either have too much or too little output, with poor to no wax potting and lousy note definition. How is that changing to better pickups will not change by a large margin?

Sure, body construction is also important for sustain, but don't forget even more expensive "budget" brands like Epiphone, LTD and etc don't utilize single piece bodies. Most of them use multiple pieces and glue them together to get a 2/3-piece body. So if thats the case, doesn't that beat the argument of "body construction?".

Woods are a different story, yes, I do agree, lower priced guitars tend to use wrong woods or very low grade woods. Thats why you test the guitar before buying. Also, doing some research before going out to spring your hard earned cash will also do you good. Its quite irrational not at least read up a little on details on something you're planning to spend a lot on.

I hate to, but I have to disagree with your statement. I do not think brand plays a very heavy role on what works.