Some reasons why you might pay attention to your self appointed critic:-
-He announces himself,"I'm the producer of Radio 4's "Book at Bedtime"...
-He runs the country's top storytellers' club.
-He runs a talking book record company.
-He's a top storyteller or professional radio actor and is making genuine suggestions as to how the dramatic or humorous aspects of your technique could be improved.

Some reasons why you should roll up your eyes, mutter "Dear Me, they should not let them out.." and walk away shaking your head in a pitying fashion.
-He knows nothing about storytelling- except that he does not want to hear any.
-He has no credibility in any other field either.
-He is clearly only interested in entering into an ego race (sometimes called a p***ing competition)

The difference between a constructive critic and a low level verbal abuser is this. A critic can differentiate between "I don't like it" and "It's not good". I might not care for Opera, for example, but I don't think that Verdi is a bad composer.
A critic will offer advice on how to improve weaker areas, and will praise strengths to maintain motivation.
If your guy does neither, he is just using a veneer of politeness to give you abuse- and what respect can you have for someone who does that?
And if you don't respect the person- you have no need at all to take any notice of what they say.
The man is a wazzock- plain and simple- treat him accordingly.
Cheers
Dave