What CIC has done to you is totally unethical. On CIC website, it is clearly written that RQ may be given to an applicant when his/her declared residence within last 4 years is questionable or in doubt. However, in your case this was not the case as you were very close to Oath ceremony. After reading your post, it is imminent that CIC is also giving RQ to applicants whom they suspect will leave Canada after acquiring Canadian citizenship so that their applications will become non-routine and will get further scrutiny. Also, CIC seems to think that almost all applicants are lying on their application or will leave Canada after getting Canadian citizenship.
In your case, I think when you called CIC and informed them about your job situation that your company wants you to go to Vancouver for 4 weeks, CIC would have suspected that you are in hurry to get citizenship and may want to leave Canada ASAP and that is why you got RQ the next day. CIC did think that you are lying to them when you mentioned about your going to Vancouver for 4 weeks. CIC is suspecting everyone of lying and misrepresentation. However, this is not true. Maybe 0.5% or 1% of applicants used to lie or are lying, but 99% of applicants are honest and do not want to misrepresent. I am saying this from my experience that majority of people do not want to misrepresent, but they get penalized by CIC for telling truth.