Would you book this airport?

I was speaking to a client the other day who was looking for a Christmas cruise. He wanted to cruise the Caribbean and he wanted to cruise for at least a month. Beyond this all he was really looking for was a cheap deal as he was going to be cruising as a single passenger so he wanted to avoid any massive single person supplements.
We finally settled on a P&O back to back cruise of 28 days. The only problem was although P&O still had plenty of flights to get him out there, because it was a Christmas cruise they didn't have any flights coming back. It was then that P&O offered us a really strange solution........

As you may or may not know all airports have a 3 digit airport code. Heathrow is LHR, Miami is MIA, Venice is VCE and so on.

P&O told me I could book the outbound flights from LHR, (Heathrow), and the inbound flights as a QQQ airport.
I knew it had to be a UK airport but it wasn't a code I recognised so I asked for some more details and this is what I was told.
A QQQ grade airport is a guaranteed airport, so whilst P&O will definitely fly you back to the UK, the airport you are flying to wont be announced till three or four weeks before the cruise and could be anywhere in the UK.
As it turned out my passenger was happy to book his cruise under this basis as he lived in the Channel Islands, so it didn't matter which airport he would fly back to, he would still need to book his connecting flight, he could just do it from which ever airport he was assigned. He was just happy to get his month long Christmas cruise.

It did get me thinking though, assuming you didn't live in the Channel Islands, would you have been happy to book under this basis? I can't imagine that P&O get very many takers for it but they do offer it as an option when they're running short of flights apparently.
Have you ever booked under this basis? How did it turn out? And would you do it again?

Happy cruising