it is said in the article that the grandma admitted that she already sold some of the profit she made through mining bitcoin.
as much as I love seeing old people adapting to new technologies I think the family just made her an escape goat since
if the suspect is younger the sentence could be a lot more severe.
"Her family members were reportedly regretful for her actions and offered to refund the 6500 yuan income, which is now paid"
You have a logical theory on this situation.
But we will not know the real story behind this news.On a different note, reading the title alone seems pretty cool even if the grandma did wrong on this part.

She didn't have formal education per se but she learned how to mine btc, this is the power of internet nowadays.
You can learn a lot of stuffs via net. More than likely she's a member of a chinese crypto forum.
She can extract mining information from different net sources, so it is more than plausible that she learned how to mine from them.
having watch or read a lot of Chinese news out of curiosity Chinese people(not all of them of course) have the tendency to blame
the young or old to escape punishment. your theory about that "she learned how to mine" is more far fetched than her family letting her
take the fall so the douche bag on her family escapes the punishment.