There are a crapload of pipelines already in the ground. Google "US pipeline map." Looks like there are already a few pipelines crossing the AT. How is a pipeline all that any worse than the hundreds of road crossings?
I'd rather see the discussion be about the pipeline integrity, or maybe some sort of multi company co-op usage of the pipeline. For all I know they already do that, rather than have seven or eight of the big oil companies each building their own pipelines. I'd hope that reforestation is also part of the deal, or do they need to keep it clear of tree roots?
The fuel is going to cross the AT one way or another. Endless semi trucks ferrying it, or through a pipe. Which has the least long term impact.