Under "Moving Between Attacks" it says:
"If you take an action that includes more than one weapon attack, you can break up your movement even further by moving between those attacks..."
If you were to twin booming blade then this would be an action that includes more than one weapon attack. Does this really mean you are able to move between the two attacks of a twinned booming blade?
Note that Twinned Spell requires you to
"target a second creature in range with the same spell"
so, to me, even if this is possible, you could not move particularly far using this method as both targets need to be in range when you cast the spell.