The 60's did not have the technology we have today regarding weather. There is no excuse from a pilot perspective regarding weather unless it is in controlled airspace whereas that responsibility falls on the ATC tower since pilots are typically "head down" on land preps.
The pilot had one of two things on his mind;
"Fly through it with risk, land and get to the hotel and bang this flight attendant that dropped Viagra into my coffee"
or
"The company emphasis's using as little fuel as possible, I'll take the risk and make my log book fuel-usage look stellear"
Rippy!
Nah ... I think it's a uneducated coffee machine statement. Despite the technology available it's not always easy to go around cells. Stay away from the red stuff is not always clear cut. When you have a 80 miles wide storm front you navigate the best
through it IF you have the freedom to do so. The closer you are from the airport, the less freedom you have. Can't miss that entry gate, or deviate too much from other segments of the SID/STAR/App, especially in busy cardiac hours launch/recovery class B airports in mountainous areas.
Then there's red stuff and red stuff. Some red cells are very dense rain, some hail and some crazy donut hail, but you don't know ahead of time. Satellite weather updates only every few minutes and fast moving fronts shift the image a couple, of miles.
It's easy for the common Joe or 'Super Pilot' to blame the pilot. The reality is they do the best they can with what they have. Flying is still trick stuff and you don't always win.