I live in Campbell and I am strongly opposed to having an In N Out location at that location.
I enjoy In n Out Burger and have gone to the other locations many times; however, I used to work near the Mountain View location near Rengstorff and 101, and have seen how In N Out can increase local traffic. In N Outs tend to be open very late, and I have seen them serve many people just passing through an area, nearby a highway exit. What this does is add a LOT more traffic to an area, especially at crucial rush hour times (like 5pm-7pm when people want to grab a bite on the way home from work) as people exit the highway, order takeout (even more so with a drive thru), then get back on the highway.
This added traffic would significantly impact the traffic and safety in that area. The Hwy 17/Hamilton intersection is already the worst, most difficult, and most dangerous in the area. Adding thousands of cars exiting the highway making U turns, picking up food, then getting back onto the highway, is a bad idea. I worry that an In N Out will cause dangerously long traffic backups -- imagine even more cars trying to merge onto Hwy 17 exit lanes at the last minute, and lines lasting multiple green lines to U Turn on Hamilton.
This location would be better served by a sit-down restaurant like Elephant Bar used to be. If it's a location where people come and sit down for a while and eat, that would add much less traffic and be a better fit for this location.