IMO, never read an article about a SCOTUS opinion. Always read the opinion itself. They are not difficult to find and not difficult to read.
It doesn't look like he was under the influence at the time, but the term "driving out of his lane" does kind of give reasonable cause for drug use, but maybe thats profiling.
No, it really doesn't.
Maybe the driver was futzing with their cell phone. Maybe their eyesight has degraded but they still have a license. Maybe there was something in the road that the officer didn't see. Maybe there was a bee in the car. Maybe the passenger grabbed the wheel. Maybe the vehicle is malfunctioning (say, headlights are out). Maybe the driver hit a pothole. Maybe the lines were unclear, having been repainted. Maybe the driver was falling asleep.
The core issue here was that the police officer was finished with the traffic stop. Then he asked to do a search, and the driver refused, and then he detained the driver.
Searches are legal, but waiting for backup to conduct a search isn't?
You can't detain someone longer than is reasonable (4th Amendment), and the decision says it's only reasonable to detain someone as long as it takes to complete the traffic stop (a definition established in Illinois v. Caballes in 2005). So case law says that the 4th Amendment's "reasonable" means "as long as it takes to finish the traffic stop." By the officer's own admission, the traffic stop was complete. Since nothing incriminating had been discovered by that point, that makes further detention or search unreasonable, and that makes the it all unconstitutional.