Salam Muzammil , i think you and I are the only two people on this forum who are from Saudi Arabia on Iqama and both of us are expats . I'm Indian from Jammu and Kashmir. I'm also planning to re-apply in September of this year from CHC Riyadh . I have selected Holland College for Electronics engineering technology. We can help each other by keeping in touch through this forum regarding how to re-apply for Canada study visa, I hope you will agree. I live in Ad- Dammam- Eastern Province .
I'll try to explain what the reasons possibly mean one by one
You have not satisfied me that you would leave_____ because
1. Travel history
I think your travel history would have something to do with your past ten years of traveling this may include eg- staying in another country for prolonged periods,being refused visa to countries that was not mentioned while applying for study visa to Canada or any other points that raise an eye on your previous travelling.
2. immigration status
this could have something to with your IQAMA or current status in Saudi, either the IQAMA is close to expiry date or you did not apply for a re-entry visa to Saudi Arabia in your Passport before applying for Canada visa. The Embassy guidelines require that expats applying from Saudi issue a re-entry visa to Saudi before applying to Canada.
3. length of proposed study in Canada
I'm not quite sure why he raised this as a reason.. however from my understanding this would be in regard to your Letter of acceptance from western Ontario, maybe the start date and end date of your course was not mentioned properly in the letter ..i may be wrong on this.
and finally coming to the most amazing reason
4. limited employment prospects in my country of residence
unfortunately this reason may be a genuine one, I'll explain why he may have given this reason.
I checked the website of western Ontario for engineering, the website states that the engineering courses have clear motives on green energy, sustainability, innovative technologies. The bottom line is that the Visa officer wants you to know that the M eng degree from western Ontario would land jobs only in America and probably Europe not in your country because they have motives for sustainability. Students applying from countries like China,Nepal,Pakistan , India , Bangladesh would have same problems in explaining the Visa officer how this green technology course can land a job in their developing country, who are currently focusing on Industry driven Engineering (free from green Tech).
I hope we can discuss further about our refusals