[pfix]

I'm not familiar with retroshare but from a quick research it seems you only receive content from people you're connected with and their connections. So it should be pretty straightforward to remove toxic connections

http://retroshare.wikidot.com/en:faq#toc1 (Lost the link where there was an example on how to split a group chat if one person leaves that connected two groups)

And I can imagine it's possible like with ad block plus et al to have local blocklists in your client. Its not like we have this situation elswhere (mail, web) so...