Without more info I'd say, who knows. People fail to address problems for many bad reasons, so in this case I can't really guess the reason. In general I do think sexism is a problem that skews the way ideas and criticisms are judged in tech today, though, so it doesn't seem like an unlikely possibility.
Either way though, I suspect there's not much more that can be done to discourage such bad script examples if the editors won't even add warnings about word splitting, publish letters, or reply to readers' concerns in a way that makes the readers feel like they should keep reading and (I don't know the magazine's business model but) giving money to the magazine.
Regarding the technical issue in the example... I think the only situation where anyone familiar with shell scripting would be tempted to use a method like that would be to avoid numerous file invocations, but that only matters if there's a huge number of files...
...And in that case, it hardly seems like they could know they're named in a way that doesn't cause problems, especially since this is a situation where they don't even have reasonable suffixes that can be relied on as indicators that they are JPEG images!
