> The reports are evaluated by the network.

The network which was just shown to be 51% malicious actors? And how is it evaluated? What if the slasher is dishonest? What if it sends trillions of fake requests?

Evaluated in the same way that “does this address have enough to send to this much to this other address” is evaluated? If it isn’t valid, then a block containing it isn’t valid, and this is a thing which any client can automatically check.

What happens if you try to send trillions of invalid transactions in any sensible chain?

To whatever node your client is talking to, the invalid transactions should not be relayed. This is more of a DDOS situation than anything novelly technical. Like all computer systems, DDOS is a technical challenge that requires careful consideration.

Normally there's a fee to try and send such things to prevent such behavior. I haven't seen anything suggesting thats the case for slasher reports.

The thing here is that the validators don't need to be honest when responding to a slasher report.

Do you mean by claiming that the block containing it is invalid when it is valid, or visa versa? Or something else?

Also, how can there be a fee to trying to send an invalid transaction? Such a fee would have to be sent as part of a transaction, yes? Isn’t it just that someone spamming the network gets dropped from the gossip protocol stuff?

51% is possible, but if it happens someone has wasted (at current valuations) ~$15B gaining a majority stake in a network they are torpedoing. It would be pretty dumb to do something like that to your own investment.

So Elon Musk alone could do it on a whim, for the lolz?