Not so much a failure of understanding

Ian Black in today's Guardian:

Few of those who subsume Zionism into the narrative of western colonialism understand that what oppressed the Palestinians simultaneously represented a movement of national liberation for the Jews.

Is it that they don't understand? Isn't it rather that they simply refuse to allow? This is of critical import, since what it shows is that the very right that those 'subsumers' demand - and quite rightly - for the Palestinians, they will not extend to the Jews: the right to national self-determination.