It was noticed that replying, quoting or reporting via the iPad forums app results in a greyed out send button at the top right of the window. This issue is also noticed in the IPF.net app. The problem stems from the top line being useable. The app developers are aware of the problem and working on a fix.
The work around: tap the enter key on the keyboard and the "send" button will be enabled. This will cause two blank lines at the top of the reply, but that is a necessary evil because back spacing to the top of the reply causes the send button to be disabled again.
Credit for this temporary fix goes to Thomasjtsi, a moderator on the iPhone forums, as he was the first person to inform me of it. I'm simply posting this fix to benefit the iPad forums community.