I think you're right, actually. Looking at the PP itself, it states:
1) The development must be begun not later than the expiration of three years beginning with the date of this permission.
Reason - Required to be imposed pursuant to Section 91 of the Town and Country Planning Act 1990.
2) In these conditions, the following phrases shall have the meanings set out below:
Additional capacity – shall mean the capacity of the Etihad Stadium in excess of 47,670 seats which is provided by the development hereby approved and references to the use of the additional capacity shall include the sale of any ticket for the use of any seat within the Etihad Stadium located within either the south or north stand or pitch side seating as expanded by the development hereby approved.
Phase 1 – Shall mean the construction of the south stand and its associated public realm works;
Phase 2 – Shall mean the construction of the north stand and its associated public realm works.
Which I'd take to imply that only Phase 1 had to be started within 3 years, allowing Phase 2 to be undertaken whenever the club feel like it.
"Ferguson. Žvaka kurac."
(Ferguson. Chewing-gum cock.)
Old man in a bar in rural Bosnia.