Contrary route directions

We're off to the CC Wharfedale site at Grassington tomorrow, so idly looked at the CC recommended route. It rightly suggests turning off the A65/A59 roundabout onto the B6265, and says "avoid all other routes" (e.g. turning off in Gargrave). However, if I click on "plan a route" it takes me up the not to be recommended road.

I don't know why I looked really, as it's not far away and we know the way. I just wanted to check how long it will take to get there, as we'll be leaving home late on and arriving when all the Sunday Stragglers have left!