I cannot agree with you here. Simply injecting acetone does nothing. Acetone is a solvent, it acts by dissolving and/or holding in suspension the contaminants you want to remove....
Yeah, agreed; it is not perfect, but I have had some success using the acetone syringe to dissolve/flush out, uses up a bit of acetone, though. It is difficult to get things really clean if you can't wipe deep into the crack (sorry, couldn't resist).
I was just offering other options...(clearly the butterfly does not work well for this, but the chart table crack perhaps). Not very keen on the dremel/fill with wood-dust/epoxy personally - good for cosmetic repairs (used it many times), but the weakness introduced by the crack will still be there, and I don't know if it would hold when redrilled. Also as somebody mentioned regluing a previously glued crack is almost always a mess. So you are probably right - replacement is best, or the dutchman if space/skill allows.