I suppose that, absent a formal reimbursement request made by you, they could consider the movement of cash from the HSA to another of your accounts to be a "transfer to or use by you, or for your benefit, of any assets of the HSA" that would constitute a prohibited transaction, but, unless they charge a fee for a reimbursement request, it seems odd that they would not just consider such a transfer to be an ordinary distribution. It seems unthinkable that they would even provide a mechanism whereby you could make a cash transfer that they would consider to be anything other than an ordinary distribution. The HSA that I have has no such mechanism and the only ways that I can cause cash to be moved out of the HSA are by using the associated debit card, making an explicit reimbursement request, or requesting that a payment be made directly to a medical provider.
