Griefed in ICC run, why is this possible?

Q u o t e:
Why is this still possible?

Unfortunately it is possible because that is how the instance currently functions. If you believe there should be a way to lock specific options in the best thing you can do is post your feedback in the Suggestion forum. Our Developers and Community Managers can review the posts made there.

Q u o t e:

Is this bannable? Should I report this in game to a GM?

This is not something that we will likely be able to assist with, Cillian, as a member of your raid that person was able to interact with your Faction Leader and decline the help.

I believe a soft reset of the instance will enable the buff again.

To perform a soft reset, follow these steps:

-Have the entire party/raid exit the instance.
(Please note that players who remain inside the instance, even those who are logged out, will prevent this workaround from functioning as it should)
-Wait at least 30 minutes while every raid member remains outside of the instance.
-Re-enter the instance only after 30 minutes have elapsed.

When you re-enter the instance after completing the soft reset, all scripted events that your raid has not yet completed should now be reset and you should be able to continue raiding where you left off.

Q u o t e:

Anyway, with a pug this is not a workable solution, since you aren't going to get 25 people to stand around for 40 minutes.

Current queue times are around 2 days, so I think a reset would be a bit quicker. Not to mention that Game Masters are unable to assist in such cases, a soft reset is the only viable option.

Q u o t e:
Do the developers know people are being griefed because there is no option to turn the buff back on?

I am not a liaison with Development but they likely know that they have given the option to turn off the raid to anyone in the instance. There are many aspects to the game where it may be possible to use a functionality to the detriment of others.

There is an option to turn the buff back on but apparently not by speaking with the NPC again. It is possible that the functionality could not be implements as if it were an on/off switch. Soft resetting seems to work in this case though.

Q u o t e:

Its not actually a viable solution, for obvious reasons.

It may not be a desirable solution but that doesn't mean it isn't viable. As I said Game Masters do not possess the ability to reset the instance to present you with the buff option. The only possible method of applying that buff again is to soft reset the instance.

If you wish to continue with the buff in place that is the only available option.