[rrrrrrrrrrrryan]

"Run-on" has an actual textbook definition. This sentence is very long and clunky, and should probably be broken into two sentences for readability, but it's not a run-on.

To illustrate, this would be a run-on:

No union victory is bigger than the first win in the United States at Amazon, many union leaders regard Amazon as an existential threat to labor standards across the economy because it touches so many industries and frequently dominates them.