I was no good in physics, but I do think it would be impossible for the chemicals to be released into the tissues post-mortem; in part because the IV lines would be disconnected and either 1) they would not be clamped (not very likely, given the care regarding disposal outlined in the protocol) and the chemicals would drain more easily out the open end or 2) the lines would be clamped, and for the chemicals to flow into the tissue, they'd have to work against a vacuum-effect, wouldn't they? And not only that: For the chemicals flow within the soft tissue sufficiently for there to form a foot-long chemical burn wouldn't there have to be circulation?
Furthermore, if we accept that the IV lines were not compromised, and IF we accept the explanation - for the purpose of argument - that the needles didn't go through the veins until after death, then there's still a problem, inasmuch as the caustic agent (which caused the chemical burns) was Pancuronium bromide. If we count: Angel received according to testimony a total of 14 injections: One full course of LI, making a total of eight + 2 Sodium Pentothal =10 + 1 saline solution = 11 + 2 Pancuronium Bromide = 13 + 1 saline solution.
Meaning, the last drug which was pushed and therefore remained in the IV, if the IV lines weren't compromised, would be saline solution, which (I'm not a doctor, but I play one in my emails) should not cause those burns. Not before death, not after, not ever.
It simply makes no sense -- regardless of how much you try to give them the benefit of the doubt.
But you're right, they'll probably get away with it; for them, nothing says 'legitimacy' quite like pretending to give a shit for about a month or so.