Not really, that's not how it works. The same deal is offered to everyone. There were a certain number of places, and they are filled in seniority order. Perhaps the mix of trips was just right? Each individual would have had his reasons for bidding, or not, as the case may be.
Edited to add - not all trips by 318 pilots will be on the 318 from LCY. The balance of the month's work will be at LHR or LGW on the 320. You can guess at the payscale given that it has gone very senior...
Also, BA has 'backers' for the route - even in these impoverished times.
Pity they didn't get a few backers before wasting millions on OpenLies....