Yes, it should get you off the hook.
The random guy at the relevant authority speaks in the role of a representative of the organisation by which he/she/it is employed in a role to provide information on which enquirers rely. That role carries a legal and civil responsibility.
If you have relied in good faith in the best source of information, being the relevant correct authority, and have a reference number and notes relating to the conversation, a conversation which in most cases will have been recorded, you have met most necessary and reasonable legal obligations.
How one phrases a question, and how the reply is received, and then repeated to the respondent and receipt of their agreement that the repeat of their advice being correct will, in the majority of situations prior to Court action, be accepted as an act of good faith and as fair and reasonable risk mitigation prior to an act unless the advice goes beyond "what a reasonable person would do". In other words, if they say something outlandish such as "Yes, you can fly above 1000' and it's OK", you would reasonably reject that or research and seek an alternative opinion from within that organisation quoting to that other source the information which you thought reasonably to be incorrect.
Each of the terms used in this reply, in particular "reasonable", meet several tests that exclude wilful negligence and ignorance of law, which will have been disproven given that a legal query has taken place with the relevant authority and the jurisdiction of the authority should be reasonably proven during the conversation.
While some US laws have some oddities compared to UK, AU, CAN and other Commonwealth countries, the principles of "fair and reasonable", "reasonable person", "wilful negligence", "good faith", and "risk mitigation" remain almost universally constant in criminal, civil and tort law.
Cheers - i.