I don't think there are any LGPL licensed libraries linked or distributed by a Unity iOS build. Neither you nor I have looked carefully, but it's almost certainly not the case.
With regards to libiconv, which I don't know if Unity iOS builds use it, there is a BSD implementation of it, which is almost certainly the case also with what iOS uses.
I can't speak to the work the author of this blogpost did with regards to investigating the usage of the specific LGPL libraries. The specific examples specified would all make sense as strictly used by the Editor.
My opinion is that if you are looking for wholesale license violations by giant corporations like Unity, libraries are the wrong place. Huge corporations launder license violations by line-by-line rewriting the code and pretending their implementation is original.