From the Toque:
William Shatner was chosen to be represented on the coin because of his status as a hero to Canadians, and especially the science fiction community, which makes up approximately 80% of the Canadian population. [Really?]
Most Canadian coins are composed of standard base metals. However with Shatner on the face, they thought it more appropriate to go with a heavier metal, and ultimately chose a nickel-plated tritanium alloy. [Not gold?]
Shatner beamed with joy when told he had been selected to be on the face of the coin.
"I can't...tell you...how happy I am," he said in halting English. "No bones about it. I hope these coins...live long...and prosper...like my career."