How I attacked myself with Google Spreadsheets (2012)

How I attacked myself with Google Spreadsheets (2012)
behind-the-enemy-lines.com

I'm struggling to see why this is a legitimate design decision on their part - how is downloading a new copy every hour different from maintaining a persistent cache wherever they are storing it after download?

It does have a certain "perfect storm of good intentions" quality, but no, "prefetching" hundreds of gigabytes worth of images that the user is not looking at right now* and that will not be cached for the next time the user views it, that the user did not indicate will be changing frequently or have recently changed, and doing it every hour on the hour (according to timestamps in a screenshot), is not a "perfectly legitimate" design. Calling it that implies IMO that there is nothing Google should change about this (maybe the author does not mean that.)

Maybe I or the author are missing something here -- why did Google think it was necessary to fetch something that will not be immediately shown to the user nor will it be cached for later? I can understand the no-caching decision, but then why fetch at all if it's not needed now? Why is 1 hour supposedly short enough for some hypothetical user that wants their spreadsheet's embedded images to update automatically, but long enough to not cause damage (wasn't long enough in this case)? And I hinted at "on the hour" above because it seems like some sort of staggered refreshing would be better on the CPUs and networks involved, though it wouldn't make a difference to the author.

Even if for some reason they think fetching this aggressively and wastefully is good, it seems like it's in Google's own interest to have some kind of safety valve (bandwidth restriction, hard abort, something in between) after a few hundred megabytes on one spreadsheet's refresh cycle. If nothing else, that omission means it probably wasn't a "legitimate" design decision.

Wild theory: the author was accidentally causing the refresh somehow (or maybe purposely automated but forgotten.) Somehow it seems more likely than Google setting it up this way on purpose...

* I'm kind of assuming here, but the author doesn't mention anything like he was actively viewing the spreadsheet while the attack was happening. Even if he had it open (and with all the image-linked cells in view!) for hours on end, I stand by my other points that it's strange and not a perfect design for Google to auto-refresh in this fashion.