Allowing FBI to have any more control than they already do is bad.
It is similar to owning too much of a network, and a good example is 51%+ threats to Bitcoin.
This doesn't just mean Bitcoin networks, all networks in general.
FBI has enough power, they should not be allowed to gain more resources/power with these seized Bitcoins.
I will be using a Bitcoin tracking device to make sure I never get Bitcoins that the FBI once had and I will be able to track every company/person that accepted them.
This is very easy and possible to do.
We as a community can reject these coins all on our own.
Then at the same time you can argue that DPR shouldnt have been able to have that many bitcoins , or anyone for that matter. Inviduals could be just as dangerous as a group (like the fbi in this scenario). Thinking a guy selling drugs and putting out hits on peoples lives is less of a threat holding that many bitcoins just seems silly to me.
There's always going to be potential threats like these. I think it would go against the nature of bitcoin to say a certain person or group shouldn't be allowed to hold x amount of bitcoins though just because you personally don't trust them to do the right thing with those coins. Imagine a world of bitcoin where you can only get bitcoins if youre on an approved list and even then you can only own a certain amount, I don't like the idea of that.
With all that said, I'm still fairly confident that the FBI isn't going to do anything with these bitcoins that would severly hurt the market. Especially considering how bitcoin has moved away from just being a 'shady black market' type thing and has moved into real business's and job creation. Especially as America seems to be moving closer to allowing bitcoin to expand. Just doesn't seem likely to me that at this current stage the FBI would do something that would at this point cause a lot of people to lose their jobs and entire industries/businesses to go under. If bitcoin was still only being used to just buy drugs or launder money then I could see the FBI wanting to hurt it, when you have real legitmate businesses and people involved in bitcoin now though it seems a lot less likely..... heck I wouldn't be suprised if theres multiple people in the FBI who have their own personal holdings in bitcoin.
edit: btw, why would you care if you own coins the fbi once had in their possession. If you go to the ATM tomorrow and you receive cash that was once touched by police or the fbi do you really care ? It's still cash regardless of who it passed through at one point. Weither the FBI use to hold it or not, it's still the same bitcoin.