Let him follow his passion but if he has not identified it yet, let him do either civil or telecommunications passionately. Architecture demands talent and passion not just grades.
I did telecommunications and for the 2 years I've out here it's not been soo bad though I'm doing more of IT than telecoms.
Lakini kama ni pesa, he might as well do anything, I work with guys I was in high school with who did business related courses and they earn more than I do. By the time nimalize shule they'd already worked for an year or so.

The engineering field is very tricky in the country and to succeed just like said earlier one has to be very passionate .In Kenya,Jobs are few and competition is extremely high almost suicidal.Ladies have more opportunities and I would advice more ladies to pursue engineering courses in Kenya.But for young Men,you must be prepared to really hustle post graduation.I did telecommunication engineering.went for almost 6 years without any meaningful employment.My breakthrough came when I did a diploma course in airline ticketing..So if he chooses engineering let him be prepared to go the extra mile.

He could do any of the courses for one year; get a feel of what it's like, etc.
In the 2nd year, if he feels something else is better, he could switch courses.

There's usually a deadline, though.

Also, let him know that only 64% of people who enroll for the course graduate when they're supposed to. In short, si mchezo.