No sarcasm, that honestly sounds pretty cheap. About the price of a mid-level FAANG SWE.
However that sum is low. You need 24/7 security people at watch, both guarding him and the home and then also key family members.
It is possible that he prefers a low attention detail, which reduces cost. But we're still easily talking about a mid two digit number for full-time personal.
It is however likely that different aspects are accounted differently (general company estate security etc.)
Include in the equation that Satoshi additionally likely is a person who puts a high value on privacy, given that they ensured to be anonymous up to now.