That's good advice for this hypothetical character ... but doesn't it sound a little like the advice that's been given with regards to 4e character conversions?
Basically, you're telling this guy to make some compromises, and maybe drop something because it's not optimal. Rogue + longsword: either go with a rapier or shortsword (compromise), or forget the longsword or eat the penalties associated with a rogue using anything other than light blades (dropping/eating the unoptimal).
Like Fifth Element said, it's a class-based system, just like 3.x is - sometimes you have to compromise, and sometimes the concept you want just doesn't fit the given framework at all.