A quote from the article you linked:
The first mention of the Irish Pale is in a document of 1446–7. Though there was an attempt later in the century to enclose the Pale by a bank and ditch (which was never completed), there never was a literal fence around it. The expression has often been claimed to originate in one or other of these pales, most often the Irish one, but the earliest appearance of 1720 for beyond the pale is very late if it’s linked to the Irish one and much too early for the Russian one.
The earliest figurative sense that’s linked to the idiom was of a sphere of activity or interest, a branch of study or a body of knowledge, which comes from the same idea of an enclosed or contained area; we use field in much the same way. This turned up first in 1483 in one of the earliest printed books in English, The Golden Legende, a translation by William Caxton of a French work. This is a much later example:
By its conversion England was first brought, not only within the pale of the Christian Church, but within the pale of the general political society of Europe.
The History of the Norman Conquest, by Ernest A Freeman, 1867.
Our sense seems part to have grown out of this, since people who exist outside such a conceptual pale are not our kind and do not share our values, beliefs or customs.
This is absolutely in accord with the word arising from the Irish Pale. The etymologist seems to be in denial for some reason, about the brutal reality of the self concept of the conquerors and the concept they had of those not yet conquered, and he probably hasn't ever visited the remains of the original Pale, which are still visible today complete with the ruins of its associated fortifications.
www.historyireland.com/early-modern-history-1500-1700/the-english-palea-failed-entity/
The Pale and the concept of 'two nations' that is attempted to enforce and which it has signified ever since it was first erected.
...to be English conveyed certain rights and privileges as the king’s subjects (whether born in Ireland, Wales or England): in the Pale, discriminatory legislation against ‘the king’s Irish enemies’ was actively enforced. And given the frontier context—two nations, laws and cultures, and a pervading rhetoric of difference—the Palesmen were highly sensitive to their English identity, because to be English was to be free and civilised, whereas Irishness was synonymous with servitude and savagery. It is, in any case, a nonsense to talk about ‘Anglo-Irish subjects’: there was no such legal category. Second, during the later phase of Tudor expansion, English incomprehension of the refusal of that ‘stubborn, rude and most barbarous people’ to embrace the benefits of ‘English civility’ so magnanimously offered helps to explain the more brutal treatment of ‘the wild Irish’ that followed.