Well that's not what I was saying.

Example: If say a person goes to the middle east and fights then they get stuck and want to come home. What country do you think will help if they find out they are dual citizens? They will both pass the blame on either country.

In this case its meaningless as the UK probably won't want to keep a wanted criminal at the expense of our diplomatic relations.

But that entirely depends if the USA request extradition. I doubt they will, but they could.

But If someone commits a crime and runs away then they decide to go back into the USA some point in the future expect to be arrested.

But yes they could extradite with or without dual citizenship.