By the way, the quote only applies to marriages inside consulates or embassies "foreign mission in Canada". However if you marry by proxy in lets say the US (some states allow proxy marriages) these marriages are valid in Canada and anywhere else in the world.
This also is from OP 2
"At a proxy marriage one of the participants is not present and has named a proxy to represent him or her. If the law of the country in which the marriage ceremony was performed permits proxy marriages, they are legal marriages for immigration purposes, provided they are legal under Canadian federal law. See definition of “marriage” above and also Section 5.27 above." These speaks to marriage laws in the country in which the marriage took place."
And the federal regulation that applies is as follows:
The federal Marriage (Prohibited Degrees) Act (S.C. 1990, c. 46) [2] prevents the following persons from getting married:
2. (1) Subject to subsection (2), persons related by consanguinity, affinity or adoption are not prohibited from marrying each other by reason only of their relationship. (2) No person shall marry another person if they are related (a) lineally by consanguinity or adoption; (b) as brother and sister by consanguinity, whether by the whole blood or by the half-blood; or (c) as brother and sister by adoption.
Therefore, if Nairobi recognizes proxy marriages as legal, and the marriage was not between 2 people as listed under the federal regulation the marriage is legal and recognized in Canada.