Hotel Tango
My reasoning is that an airport of LGW's size should NOT be understaffed and SHOULD be able to handle diversions effectively.
They are a commercial company - who will pay for that? If they over staff 365 days for the occasional divert, that cost will be spread across ALL their customers. If the divert happens and all goes smoothly - the pax will think the carrier did it all, not the airport. The pax are NOT going to think, "Oh those lovely people at LGW, I'm going to use them again."
An airline of Air India's stature SHOULD have contigency plans in place for such diversions and the staff to handle it.
Quite possibly, and put up all the fares to cover the cost at all their regular alternates. I have never travelled AI but this thread tells me that I might want to avoid them. That's the commercial reality.
As a passenger if I was held on an aircraft on the ground for 9 hours (at my destination city) I would be seriously miffed and I would not be dissuaded by a salvo of excuses.
Sure, you would be free to sue them and never use them again and go onto public forums to denounce them.
Irrespective of standard operating procedures for the ground crew of all carriers - in a recession that is the worst since the Depression - and you have the shareholders breathing down your neck- watchya goin' ta do?
A friend of mine works at a private hospital where they are almost constantly under staffed - just to save money. The hospital trumpets how much they care for their patients. Same story, different place.