If it is who I think, this was discussed upthread. I’ll find the link [addendum: never mind, bouteloua posted the method]
Basically, yes, you can exclude a user from your searches.
If it helps any, it isn’t personal; that user is rather brusque with everyone. Also, you can sometimes ignore unknowns from users with older accounts and thousands of observations (at least for a few hours or days), as these users often have a process that means those observations won’t remain as unknowns: https://forum.inaturalist.org/t/why-do-some-serious-power-users-add-so-many-unknown-observations/282