I think what we have here is a difference in vocabulary rather than in opinion.  Ferrylodge seems to understand the word "disavow" to mean much the same as "renounce".  She used to support the bridge, then she changed her mind and renounced, or disavowed it.  But  this dictionary definition seems to support the atyourservice's understanding.  In 2007 Palin reversed her previous support for the bridge, but she didn't disavow it; that is, she acknowledged that she used to support it, but no longer did.  In 2008 she is alleged to have disavowed her support, that is to have claimed that she never supported it in the first place.  We can argue whether this is in fact the case, but at least let's agree on what the word means.