Yeah, I wondered that too Sven but as my system will go on a solo PC with no networking capabilities AT ALL and EVER I quickly dismissed the security side of things. You could always download the apps separately such as Hyperspin, RocketLauncher etc from their source sites and replace the imaged ones. I posted earlier that there is a good Linux viewer/writer out there for windows after all and with it I was able to extract what I wanted form the Pie images I had D/L'd. (I changed my mind from using a Pie to a PC-based cab). The only security issues might come from the added tools and utilities that come with a (PC) package but they have been written by clever well-meaning enthusiasts not dark, mentally crippled anarchists wishing to take over the world ?
My advice but is just that, no more, is to let it go. or separate the unit from the net. Unless updating media through a paid-for service I see little reason to connect into a home network but that's just me. Think about the reason/s you want your Pie connected.