I was explaining how the word legitimate us used and has to be understood when speaking in linguistics, also in academic contexts, for instance, because it is not synonymous of "legal". Since I was speaking in English, I used an authoritative source (and I explained how in English there is also linguistic authority) to explain that. CK Evans asked me for an English example where a name breaks a rule and I apported examples of English spelling rules (the spelling rules always are conventional, in any language, but they are rules and I said that the rules and standards depend on the group or groups having power). That is all.
If the concept of rule applied to English is not pleasant, if the concept that even a language without a linguistic regulator type academy as is the case of the English has elements (speakers, institutions...) with linguistic authority is a new one for some speakers, if the spelling rules should not be more rules and the spelling should be a free market, if any name and word should be immediately considered a rule in itself after its introduction and never a spurious form... that is all another thing that escape of the intended purpose of explain what one speaker means when saying "legitimate name" (or "legitimate form" when speaking of toponymy and general vocabulary).