No surprise that 20% of the population support his views, and no reason to think that it reflects very badly on Ireland compared to any other country. At least over 50% of a small turnout supported the man who was clearly the most qualified to do the job. I don't think it shows Ireland in any significantly different light thatn most other countries. A proportion of the 20% would have a variety of other reasons for giving Casey a vote.
Sure it's only 20% of 46% which is just a little over 8% of the general population.