Patriotism is loving one's own country, racism is disliking those from other ethnic backgrounds.
Whilst the statement on those shirts might not be racist, it is ignorant. It suggests that if you criticise Australia then you're not a patriot. Blind acceptance of social positions is a sure way to ruin, it is important that we are all critical of what happens around us, by which I mean we should question what we do, what others do, and consider whether it is reasonable or acceptable.
I believe that Australians are on the whole, greatly accepting and tolerant of other cultures and practices, which is a good thing and has enriched our country. Of course this does not mean we should accept everything and anything, and we should not simply allow our own national culture to be devoured by some external influences. But what is our current national identity? The one I grew up with; the stockman, the bronzed Aussie lifesaver, the digger in the trenches really doesn't seem to reflect where we are as a nation anymore.
Do we want to become a country of gutter mouth slobs? Ignorant, isolationist and xenophobic? Then we'd be the USA, or possibly Britain, or any of the despotic third world countries in which we see so much suffering.
Let us be a proud nation; one of equals, where we do accept those from elsewhere but expect that they show their gratitude for being here, as we acknowledge our good fortune for the same thing.