Even if you place the remains in an unmarked grave, people will find it. Some may even be tempted to dig up the body, cut of it's genitals, place them in his mouth and then drag him through the streets of Boston. Not that I'm suggesting that. Although it would be "Wicked Awesome" to see Tsarnaev get what he deserves.
Instead of all that I'll step up and be the big man. I will take that body. I got a shovel and could use the compost. Nothing makes a garden grow little a rotting corpse. So if anyone is willing to pay to ship the body to the West Coast and help me dig a hole deep enough I will gladly quietly bury the bastard in my backyard garden.
Or just cremate the remains and dump them in the nearest trash bin. No one will care and we can get to healing and focusing on the victims and families that need our help. Because there is nothing we can do to erase what happened and moving forward in the only direction we can go and that's The Bitter Truth.