Throw the easy outs away - they are trash for stuff like this. If that thing shears off (which they usually do with any kind of use like this) you're in for a world of hurt trying to get that thing out, that material is a pain to work with. it's extremely hard but very brittle (like concrete blocks). can hold thousands of pounds but light taps break them.
1. get the bolt out...drill it. high quality machinist grade bits are your friend. keep them oiled and from overheating. drill from the *bottom* of the bolt so you are esesentially "loosening" the bolt as you drill...the right handed drilling from the bottom is like a left handed "loosening" motion from the top/head side of the bolt. and it may spin out.
left handed drill bits are great for bolt extraction...but this is a rare case where you can get to the bolt from the other side.
2. if the threads are damaged or you have to drill it out larger - install a bigger bolt with a nut.
3. take the knuckle off and have a machine shop get it out, they do this stuff all day long and will have no issues getting it out and saving your threads. might be worth the $50 or so to have them do it and save you the grief, tools, possible damage of the threads, etc.
4. replace with a used knuckle