I think you already answered your question, to burn bitcoins basically. Don't forget that every bitcoin burned adds value to the whole supply, so this cool bloke out there probably thought of burning some of his bitcoins whilst at the same time cementing himself in the history, I mean we're talking about him right now, so I guess it works?
Obviously that's curious, but there are 2 things we know for sure:
1. Satoshi is 4
BTC richer now

2. The coins aren't lost unless Satoshi has no access to the private keys.
ps: If you want to be absolutely sure that you burn some coins, you can generate a wallet, send money to the address and make sure to forget the private key, or burn it, or destroy it, or demolish the building where you have saved it.
Well since we haven't heard from the guy I guess it's safe to say that he lost his keys, or maybe even did the same things you stated lmao. kiddings aside I can point to clout as to why they did this. They wanna be topical and be talked about probably in this forum, and they succeeded coz now we're talking about them.