2018 Sep, Q3,(a) (iii), gian on derecognition of an intangible asset

Dear Tutor

could you please help me to understand about the gain on derecognition of an intangible asset?

What the published answer is trying to say? I assume the examiner wants students to understand what ” Revenue” really is. There are two reasons for not recognising it as revenue:
1. it’s not the company’s ordinary business activities
2. this intangible assest has impaired, so it’s not bought for sale

But what is exactly the difference on accounting treatment or any accounting meaning for it, recognised Revenue or Profit? to me, it’s only credit to revenue or profti on P&L. I could be completely wrong.

Many thanks