I do not know what Protestant made such a claim, but it sounds like you are putting up a straw man argument.
What Christians disagree with Roman Catholics and their evaluation is that she was born without sin, and therefore equal to Christ in human perfection.
In fact, her 'immaculate conception' would have been a greater miracle than the Lord's virgin birth, since Mary was born in the normal way and yet without receiving the adamic sin nature which comes through the man.
But she is not the One for whom all things were created, the Firstborn of every creature, and yet this is what Catholic theology claims.
[Emphasis duh]
Now you say :
I do not know what Protestant made such a claim, but it sounds like you are putting up a straw man argument.1000 Silverlings said it. (Mind you, I AM just assuming he is a Protestant. The way he badmouths sheep and goats, I think the evidence is good.)
Have I settled that to your satisfaction? Does it still sound like I am putting up a straw man argument?
I keep forgetting your theory of how sin is transmitted. Sorry. I really had never heard it before, so it's taking a while to sink in.