This is another fairly silly suggestion of Cassidy’s. According to Cassidy, his Irish grandfather was nicknamed Boliver and when he started to look for Irish derivations for words, he suddenly realised that his grandfather had been called Boliver because this was Irish, and represented the words bailbhe [boliva] or balbhán [balawaan], which come from balbh meaning ‘dumb’ or ‘unable to speak’. This was because, according to Cassidy, his grandfather was notoriously quiet.
Now, it is clear that Cassidy was never told by anyone in his family that his grandfather had been called Boliver because it’s the Irish for quiet. If he had, he would have made more of it. He ‘worked it out’ after his great revelation about the influence of Irish on English. And of course, we have no evidence that Cassidy’s grandfather was particularly quiet. After all, Cassidy was a fantasist and he could easily have made this up after seeing what bailbhe meant!
So, why don’t I believe that it comes from balbhán or bailbhe? Firstly, there are kinder words for silent or laconic. Grusach, ciúin, beagfhoclach, béaldruidte. Then balbhán (a dumb person, a person unable to speak) doesn’t sound a lot like Boliver, so I think it’s out. And bailbhe is an abstract noun meaning dumbness. Irish nicknames are simply not formed out of abstract nouns. I can think of absolutely no examples of nicknames formed this way. Mostly they are formed from adjectives. When they are formed from nouns, they are in the genitive (Seán an Díomais, for example). So it’s quite unlikely that a noun like bailbhe would be used as a nickname.
There is also a question about what else Boliver might mean. After all, Simón Bolívar was the revolutionary saviour of Latin America and throughout the twentieth century, his image was on advertising posters and cigar boxes all over the States. Could it be that Cassidy’s grandfather looked like Bolívar, that he had the same moustache and sideburns, or that he was fond of cigars? Isn’t this a more likely explanation? Or does it come from Oliver?
Chance of Cassidy being correct: not very likely, in my opinion!