I’m not making it up - 
someone ask - they answered, at least that’s the answer along with the “examples” in the KB article.
Sorry for the sarcasm - it’s not for you to decide. 
When asked what was included with firmware upgrade, responded with " be gibberish to most people without an advanced understanding of HLS streaming or Linux" - that’s subjective… but concluded it’s “trade secrets”. It’s likely an experienced developer with a background in all the opensource software running their tablo already knows the intricate details.
It’s been posted a couple of times where Nuvyyo does collect user data, which I presume would require some internet usage, does not specify if it’s part of “maintenance mode”.
Speculation: guide data collection is part of it’s maintenance. You’ve noted the flashing light without internet, and noted the guide update time once internet was connected. So, it’s likely it does what it can offline… then what’s left if/when it gets online.