Being devils advocate here, whats the beef? This isn't the case of a completely uninformed passenger having a pop that the pilots "must be drunk because they flew a go around" (happened in the UK). It's someone reporting concerns that a large number of professional pilots have considered someones operating practice dubious! For all we know someone with more clout may have already reported it to the FAA. The FAA aren't going to suspend Iberias operations to the USA, and they have no power to take action against the individual pilots. I'm sure somewhere earlier in the thread it was posted that Iberia are now investigating the incident, and if it happened as LTD described it (and I have no reason to doubt that it did) I think it's entirely appropriate that they cover their rear by finding out if they have an icing maverick in their midst. For the FAAs part, it can't hurt for them to audit Iberias de-icing policy if the circumstances LTD reports are true.
For what it's worth I doubt the FAA will give much credence to a report based on an internet chat room but if you believe that LTDs initial post is true then where's the problem?