There is nothing wrong with the customized plates. Austria really ought to stop being so communitarian about this along with a handful of immigrant-related issues.
In this case I recalled Austria also having laws discriminating against Muslims and seekers of asylum, laws banning symbols and organizations related to Nazism and communism, and subtle forms of discrimination in place against same-sex couples. It is quite possible, however, the OP triggered memories of readings on Germany, Poland, and Switzerland that were then mistakenly attributed to Austria?
You indeed mixed up something here:
* Austria has no law discriminating against Muslims (the "Austrian Muslim Law" is already 100 years old and regarded even by all Muslim Organisations here as a pretty good one and helping integration).
* Austria (like Germany) bans Nazi-symbols and organisations, yeah. That is due to the history of course and pretty common sense and has uniform backing (other than within the FPÖ). Austria does not ban any Communist symbols or organisations though (there's even the KPÖ here).
* asylum seekers: Do you know that Austria already ranks 3rd in the EU in per capita asylum seeker numbers ? This year, 35.000 asylum seekers came to Austria (only Sweden and Malta have higher per capita numbers). Not only do all of them get adequate quarters until their asylum requests are processed, they also get 600€ a month in "basic income" (which is just 200€ below the minimum pension of an old woman for example who worked 40 years and paid into the system, which irks a lot of people here). Which means, Austria is not only doing its fair share to take in asylum seekers and refugees (contrary to other lazy countries such as France or Poland), but also giving them a good headstart and enabling them a good stay here. Did you ever hear about the catastrophic situation in some southern countries' asylum seeker quarters (such as Greece) ? Austria is paradise for asylum seekers compared with that.
* "subtle forms of discrimination in place against same-sex couples": Well, there's no full marriage equality here yet, only civil unions (which differ in ca. 30 points compared with the traditional marriage). But there's no more "discrimination" here than in other western European countries who still have no gay marriage in place.