Ah this is where semantics fail us! It reads: "Modify
VT-d Capability will be unsupported after update BIOS." In BIOS terms this means the capability to modify VT-d will be disabled, meaning that if the chip supports it, it will be enabled. I have a feeling that maybe people were attempting to turn it on when their CPU didn't support the feature and running into problems. For instance, I can modify the VT-d option, but it was enabled by default on my system.
Unfortunately (as is the case in many instances) something might be lost in translation. It could mean that it is not even available.
Still even more interesting about how this is worded is the term "Unsupported." They could have said "Discontinued" or "Removed," but they chose another word that is very ambiguous. This could simply mean that they do not support any issues that arise from using this feature (like not booting, etc.)
Only time will tell, but let's not be hasty.