Does the flashed bios allow you to boot with the Broadcom card?
Assuming the bios v2.35 you flashed was edited to remove the Whitelist, then I would say no, you can't update the Bios without the Whitelist restrictions returning. As the Whitelist will be written in the latest version of the bios the same as it was in the original v2.35 bios (that I assume you overwrote).
You or someone would need to edit the new Bios (v 2.52) to remove the Whitelist before you could use it in your laptop with the Broadcom WiFi/BT card.
The question is do you need the latest Bios for any specific aspect that is fixed in the new version? Or can you continue with the current Bios, where the Whitelist has been removed?
It is a Haswell laptop, so it is not as if you are going to swap the CPU or any significant component, other than the WiFi/BT card. You may look at updating the memory but that wouldn't be limited or change with the replacement of the Bios with a new version.
The Flashed Bios v2.35, if working as expected, should be retained and used going forward with the Broadcom WiFi/BT card.