If you've bought something using a Google account, it won't be marked as inactive even if you don't log into it. So it could be possible that he died in a car accident or something, but his blog will just keep on trucking along for years and years because he bought an app for his phone from the Google Play Store.
Yes, you can take measures to avoid your account being marked inactive but A) not as easy as "it's Google, you can trust it" and B) Google could change their minds about this stuff and go on a deletion spree at any moment, or even shut down blogspot entirely, it's not like they haven't shown form previously.
