PS: I've just published a follow-up article!
UserAuthority (UA): explanations, applications and implications
PS2: you mentioned your father bought steem as an asset, as an investment therefore, not as a blogging tool. From the perspective of his own investment him not voting often leads to missed-out Curation Rewards for him. That's what I meant ;-)
That simply does not change the fact that his missed-out rewards are the gained-rewards of others.
I mean take me as an example, over half of my SP is delegated to benefit others. That equals missed out curation rewards. It is money that I earned and spent on steem.
Anyway, I didn't mean to give investment advice ;-)
Just don't worry your father will be falsely identified as a spammer or bot: he won't