I tend to disagree with the author on this. Reading actual words takes time (and, for me, mental energy). I have to look at each character, say the word in my head, then visualize what action that word means. Where as icons have a lot more built in meaning (but lack specificity). I tend to use them as a _local_ fuzzy filter (unless it's a common, well known icon like share) then read the words to understand exactly what they mean.
In other words, I'm not using icons to find a single action. I'm using icons to quickly understand the available options to me. Meaning, they're only there to help me compare and contrast options within the same visual context. It's fine for the same action to have different icons in different places. When I'm looking at the "File" menu, I'm not really concerned what the action looks like on the toolbar (let alone a different app).
In other words, I'm not using icons to find a single action. I'm using icons to quickly understand the available options to me. Meaning, they're only there to help me compare and contrast options within the same visual context. It's fine for the same action to have different icons in different places. When I'm looking at the "File" menu, I'm not really concerned what the action looks like on the toolbar (let alone a different app).