EEA Family Permit - What does travelling together mean?

[werdendann]

On the Home Office website it states:

https://www.gov.uk/family-permit/eligibility

"Applying as a family member or extended family member
The EEA citizen you’re joining must either:

[..]
- be travelling with you to the UK within 6 months of the date of your application"

What is the exact meaning of that rule, regarding my specific situation?

Chinese citizens is married to a German citizen. Both are living in Germany.
Chinese citizens has received an UK Entry Clearance (EEA Family Permit).

Both will be flying from Germany to the UK for one week - together. They will be on the same flight and approach the UK Border Agent at the same time at Heathrow. During the stay the German citizen, however, will travel to a third country. The German citizen will return after a couple of days back to the UK. After that both will leave the UK together to fly back to Germany.

I am not certain, whether this is legal.
My question: Does the EU citizens has to be in the UK all the time - as is his non-EU spouse?

The ticket of the German citizen is Germany - Heathrow (long stopover) - Third Country - Heathrow (long stopover) - Germany.
The ticket of the Chinese citizen is Germany - Heathrow - Germany.
Both will stay the first night in London.

[werdendann]

Would it make sense to book for the Chinese citizen a cheap Ryanair ticket out of the UK the next morning - with a departure time earlier than the departure time for the German citizen (going to a Third Country the next day)?