It’s possible that Diggle’s perspective as a man whose life was fundamentally changed will get through to Barry and strengthen his resolve not to mess with time any more than he already has.
A firm talking-to from Diggle isn’t exactly the Airplane!-esque slap train that I was pitching for Barry as punishment for Flashpoint, but it would be much better than nothing.
Most of the conflicts that Barry has faced over on The Flash have either been resolved quickly or occurred relatively recently in the timeline.
David Ramsey’s reveal to ComicBook.com that Diggle will have a somewhat compassionate response to Barry’s actions is a sign that Arrow will take the time to address what happened with Flashpoint rather than just use Flashpoint as an excuse to set up Connor Hawke without taking the time to write Lyla through another pregnancy.