Clearly salvaging something that would otherwise be wasted is not stealing in any morally intelligible sense. However it would be reasonable for there to be a restriction on people doing it in a way that was highly dangerous, as was the case in the tragedy that underlies this thread.

Apart from the exception of public safety, then where there are laws which treat salvage of stuff that would otherwise go to waste as stealing, they are bad laws, which have no ethical status. There is a right, and indeed a duty, to resist such laws.

This sort of absurdity came up in the case of Katrina, where people engaged in salvaging foodstuffs were described as "looters".