A small point: the article suggests that "anyone traveling on the 10th Street Bypass or Fort Duquesne Boulevard, past the Fort Duquesne Bridge" would see the mural, but no, if you were on either of those roads you wouldn't see the mural, as it would be under you. You'd need to be on the riverfront trail, or boating on the river, or on the opposite bank to get a good view of the mural.
A shuttle between Hazelwood, The Run, and Oakland could be a good thing, if it is done right, namely it should be operated by PAT Transit, it should have stops in The Run, there should be parking restrictions to avoid turning The Run streets into a park-and-ride lots, and the road should have a low speed limit and should not be used as a road by police on a daily basis, as the Junction Hollow Trail has been in the past. Without this shuttle, there would be more single-occupancy cars on Irvine St, Second Ave, Swinburne St, and Greenfield Ave.
The Second Amendment does not guarantee that all people can carry any gun anywhere they want. Past Supreme Court decisions have put limits on that right. For example, in the Heller case of 2008, Justice Scalia wrote "Like most rights, the Second Amendment right is not unlimited. It is not a right to keep and carry any weapon whatsoever in any manner whatsoever and for whatever purpose."
I'm glad that Giant Eagle is asking people who carry guns to stay away. They should go further and ban guns from their stores. They're a private company. They have that right.
Guns make us less safe, so the fewer non-professionals there are toting guns in public, the safer we all are.