Technically the webmaster didn't deliberately alter the source therefore didn't break the TOS no more than the webmaster is responsible for javascript being altered by proxy sites which happens all the time.

I would suspect this isn't the first case of AdSense on mod_pagespeed and I'm sure they're aware of the issue as the Googlebot media-partner crawlers do download each web page and analyze it's content, which I assume includes analyzing the AdSense javascript embedded in the page. My experience has been that if anything is automatically found to violate the T&Cs, AdSense usually turns off the ads in real-time and will re-enable them when technical errors are corrected.

Therefore, I assume mod_pagespeed hasn't done anything they disapprove of or those ads would no longer function.

FYI, I've personally had permission to edit/alter the AdSense javascript once upon a time so never make the assumption you know the situation based solely on the T&Cs alone.

Yea, me too.

The purpose of the post was to alert Adsense webmasters that they may, unknowingly, be altering the Adsense code. A more appropriate title for the post might have been:
Are you unknowingly breaking the Adsense Terms?

Both mod_pagespeed, and Drupal jQuery LazyLoad, are altering the Adsense code. Webmasters have expressed concern at the Drupal site:
[drupal.org...] The resolution to this Drupal issue was to post a warning notice to webmasters that using LazyLoad may break the Adsense Terms and Conditions. Unfortunate webmasters may discover too late that their Adsense code has been altered without their knowledge!

Therefore, I assume mod_pagespeed hasn't done anything they disapprove of or those ads would no longer function.

It's clear, over time, that Media Bot is very very forgiving. It's also apparent that, without "express..." permission, many sites have altered the adsense code; however Adsense ads still render. It appears the Adsense staff only pursue blatant alterations of the code and its execution. BUT, the terms are quite concise:
[google.com...]

....including without limitation by not modifying the JavaScript or other programming provided to You by Google in any way, unless expressly authorized in writing by Google (including by electronic mail).

The terms are also quite concise that "some" may have be given express authorization to alter the code. As a webmaster, I might be very concerned about losing Google Adsense "privileges" if the code were altered in anyway that could be construed as breaking the Adsense T&C's, frequently referred to as the TOS.

FYI, I've personally had permission to edit/alter the AdSense javascript once upon a time so never make the assumption you know the situation based solely on the T&Cs alone.

You seem to have a competitive advantage, as do the premium publishers, but, I'm not quite sure why "I" needed to know this? Clarification? Again the T&C's specify that there may be "expressly authorized" exceptions out there.