Originally Posted by
occasional
A quick look at Wikipedia produces
"Terms can be implied into contracts according to the custom of the market in which the contracting parties are operating."
I would suggest that seating parties together is a longstanding custom in the aviation market and that it is therefore an implied term of the contract.
Unless expressly stated otherwise which they expressly do state on the T&Cs that random selection applies in certain specific circumstances. Implied meaning is redundant in that case.
The question arises, are the T&Cs any more onerous than the majority of other airlines? [that's a rhetorical question btw].
This is the legal benchmark of proof and in my personal opinion, contractually they are fair and balanced through providing a passenger with choice and alternative which is what is important.