At the ISAF Sailing Committee meeting on the 23/24 April 2004, under the heading 2008 Olympic Regatta, the following paragraph was included.
(vi) Hobie 16
It was noted that the IHCA had not put forward the class and that the Hobie 16 does not reflect multihull racing at its most demanding. Also it
was considered that it is not particularly crew weight tolerant.
http://www.sailing.org/meetings/minutes/2004_SC_24_04.pdf

I am sure that I saw somewhere else that the Mexicans had not followed up on their proposal, but I cannot find it at the moment.