Thanks for reaching out. Those licensing issues are always tricky. I'm no expert, but I believe that the intention of that license is to allowed usage if the IconExperience (by INCORS) imagery within Openfire, but restrict its usage to Openfire. My understanding of that part of the license is that the icons can be used freely, but only as part of Openfire. In other words: you can't extract the icons from Openfire and use them for another purpose. So, as long as your Openfire-based product complies with the Apache 2.0 license, and you do not use those images in your proprietary code, I think you're OK.
Just to be sure, I've sent an email to INCORS at their listed address. Hopefully, they will comment on the issue.
I hope this helps!
For the record: I never got a response.