The ban evasion rule, like some other rules (e.g. trolling) really isn't working the way it should and that makes it tempting to use the trust system to make up for it, but we shouldn't use red trust for something that doesn't indicate high risk in trading. Neutral - probably fine.
I tend to agree, although I'm pretty sure I've given ban evaders and plagiarists negative trust in the past when it became clear to me that moderators weren't going to take care of the problem. At least with the DT neg, that scuttles their chances of earning money here when they should be permabanned....but I don't do that anymore and it isn't the right way to use the trust system.
Neutral feedback in these sorts of instances doesn't really do much of anything except act as a placemarker for those who might forget that the account should have been banned. It isn't even worth the effort IMO, but to each his own.
Having said all that, if there were any DT members tagging ban evaders and/or plagiarists, I certainly wouldn't exclude them from my trust list for doing that. It's not trust system abuse, IMO, just a wee bit of misuse.