No, he is not immune. This isn't the effect of an obstacle, it's the effect of a Seismic Torpedo.

Almost answered this way as well, but I pulled up Dash's card an had to question it myself. How can Dash be in Range 1 of something he's ignoring? Definitely worth the ask; thanks OP.

I'm ignoring my cat right now. I'm still sat next to the bugger.

I think the cat is ignoring you...

In my opinion, there is how the card is worded vs. how we all know FFG meant it to be played. If I were ruling it, Dash rolls.