Welcome to the forum, @farr1.
There is very little hatred on here towards anyone in/from Mayo. I think you will find generous amounts of genuine respect towards a county that probably could have had one or two All-Irelands over the last 6 years, but for arguably the greatest Dublin team ever, and one of the best teams ever, overall. We, as Dublin fans, are privileged to be witnessing this Dublin team but we also recognise that part of what makes this Dublin team great is the quality and intensity of games against teams like Mayo and Kerry in that period.
If you read through the various, relevant threads, you will find a lot of goodwill towards Mayo and you will certainly get a sense that should Mayo ultimately prevail one of these years, you will get a lot of genuine kudos from most Dubs on here.
As for this particular thread, the creator has caricatured some prominent members of the Mayo set up and it is not done, as far as I can see, in any way demeaning or personally abusive. The humour is probably aimed more at the perception within which people like Aidan O’Shea are held in Dublin, Mayo and well beyond.
We are all Gaels and we are what make Gaelic Games the enjoyable spectacles they are and also the community focal points that they provide, particularly in more rural areas in counties such as Mayo and Donegal.
Happy Christmas to you. Best wishes for 2018. I think Mayo will still feature in the business end of next year’s championship but will probably fall agonisingly short, again.