it was indeed an easy and pleasant task to go through the clear and well written article by Iliopoulos . It says all you may want to know about the GIM mechanism, quotations are correct and fair. Chapeau!
This is an excellent account of the GIM mechanism, in historical context. Most of my comments are typographical.
In the Table of Elementary Particles, I suggest placing the neutrino before the charged lepton in each pair, so the order corresponds to weak isospin +1/2, -1/2, as for the quarks.
In item (iii) below the Table, sens --> sense.
In the section, G.I.M. Mechanism, F.C.N.C. is not defined. I suggest substituting flavour-changing neutral current (F.C.N.C.)
Also in this section, only the heading is G.I.M., elsewhere GIM is used. I suggest adopting GIM everywhere. (I would also write FCNC instead of F.C.N.C., everywhere.)
In the paragraph beginning "Let me open a parenthesis," Segrè is consistently misspelled as Segré; the (Italian) grave accent should replace the (French) acute. This persists in the bibliography.
Finally, I have one suggestion for an addition. The GIM insight that quarks should come in complete weak-isospin doublets to avoid FCNC set the stage for recognizing that matched doublets of quarks and leptons not only display a superficial symmetry, but are crucial to anomaly cancellation and thus to the renormalizability of the electroweak theory. A brief addition about the Bouchiat-Iliopoulos-Meyer paper (and perhaps also the works by Gross & Jackiw and Georgi & Glashow) would help tie different threads together.
I changed "tight" to "tie" in the third line of the final section.