Could, You please tell me the way I can report that to the mods?

You can't.

Let me go over how Hive works.

There are 2 issues here.

1. Content:
   Content is published to the immutable Hive blockchain and then front-ends such as leofinance.io can choose to display what they please.

   On LeoFinance's front-end, he looks to already be muted.

   His content is not censored at the account level and he is not banned.

   No matter what, everything he writes is still published to the Hive blockchain and can be displayed by other front-ends who don't view his content as spam.

   The system is working as designed.

2. Rewards:
   But I don't think you really care about his content, you care about his voting habits affecting your rewards...

   However, there is nothing you or anybody else can do about this.

   Hive is a decentralised platform with a system of stake-based voting to distribute rewards tokens.

   As this user has staked HIVE (including delegations he has 450ish HP), he can freely use this stake as he pleases to distribute rewards.

   In his opinion, that is best done by putting everyone on an auto down-voter with his stake.

   Nobody has the power to take this away.

I know this is not what you wanted to hear, but it's the harsh reality of the decentralised Hive blockchain's stake-based rewards system.

If you want someone you call boss to be able to ban another equal user simply because you don't believe in what they're doing or saying, then Hive isn't the place for you.

The worst thing is that IDK why but his downvote has a big impact on the SEO.

It doesn't.

SEO has nothing to do with the Hive rewards system.