Your timing is off.  The 15% tax was instituted in October 2106. The effect was to immediately and precipitously drop the number of sales and cool the prices in Vancouver.  So you'd have us believe that the Victoria market went up in March 2017 due to all the people in Vancouver who couldn't sell because of the tax?

Victoria prices went up in March due to a shortage of supply; down to 1,500 MLS listings for the whole metropolitan area.

And as anyone should know, one month's stats don't reflect a market.  I have Realtor friends who tell me the market in Victoria is softening, more listings are coming on and there are far fewer bidding situations.