Firstly congratulations on your nomination. I am not sure about your situation and what you have written to CIC, but my feeling is incase your spouse is illegal in the US it would be better to send him/her to home country. CIC may have problem with spouse living in US illegally, but it should not have a problem if spouse is in home country as long as you maintain your H1-B status in US. Also, I feel by doing this CIC may want to nominate you to facilitate family reunion.
This is my feeling but you are the best judge. Before taking any decision you may want to consult a lawyer/person who is knowledgeable on both Canada and US immigration laws.
Thank you anthcott for your reply.
Does anybody has any similar experience to mine or know of any case like this. Please share.