I think it's a very reasonable attitude. The person your replying too is stating their personal position. I'm also unlikely to worry personally at the moment because there are other people much better suited to do that whose job it is to do that. There are some many things going on at any one time that reducing what we personally need to be concerned about is a pretty valid strategy.
I'm not saying one should spend one's life planning for nuclear war, H5N1 and a zombie apocalypse. Filter out first what rises to your threshold of concern. But as with a codebase that you know might have vulnerabilities: Consider what those might be, and start to prepare for them proactively. Just saying fuckit is neither useful nor a good look. Unit test your life.
