If you collect dollars, then it would be interpreted that your btc was sold to the corporation and by that you will be liable to pay Capital Gains Tax.
How did you come up with that? 
They have their transactions in their books and decided to hold, BTC went up, so there are gains to be reported.
Why were they planning to transfer the ownership to you? Do they owe you money or were they simply hoping that it will allow them to avoid taxation.
You said they were accumulating over the years, so they were reporting those coins as company assets each year, right?
No you are getting it all wrong and its because the company will not recognise it as an asset rather a liability in the books and the gain arising on such will be added to the customers deposit because the btc op has, is like a loan to the company. Now, in this case when OP is trying to withdraw, if its going to be cash then he will pay CGT because he needs to sell the bitcoin to cash but if he is withdrawing the BTC then what he did is just to defer the payment of the tax to a future date when he will be converting it to cash.
