You can play the 'this is a bad idea because' bit for almost anything. I can find a negative to grocery store greens, organic greens, lawn clippings, typical garden produce, most planted pens, etc. I sort of blame the media in part for the 'this is going to kill you' hype, but adults almost always look for and emphasis the downsides of most issues.
Most captive tortoises and humans eat grocery store greens, usually totally unwashed, and do not show any real issues from it. Torts are also pretty dang resistant to a lot of chemicals and toxins.
Treat your greens in the way that makes you happy. My personal preference- if I do anything at all- is to soak them in a large, deep container of very cold water with a cap full of vinegar for about 15-30 minutes to remove surface residue and dirt, and to rehydrate the tissues. Dry the leaves and store in a cold but humid location using whatever method works for you.
Most captive tortoises and humans eat grocery store greens, usually totally unwashed, and do not show any real issues from it. Torts are also pretty dang resistant to a lot of chemicals and toxins.
Treat your greens in the way that makes you happy. My personal preference- if I do anything at all- is to soak them in a large, deep container of very cold water with a cap full of vinegar for about 15-30 minutes to remove surface residue and dirt, and to rehydrate the tissues. Dry the leaves and store in a cold but humid location using whatever method works for you.