Not 100% certain on this but I think you will find that the Singapore Government Labour Laws, under which the pilot's contract is issued, states that in the event of redundancy then expatriates have to go before locally employed staff.
From previous experience SIA will want to apply the 'first-in-last-out' policy according to type of contract, so, a foreigner employed after an expatriate but on local terms may be retained if they don't apply redundancy to that group, but an expatriate could be terminated even though he has been employed longer.
That said, SQ will proably have their very own unique way of getting rid of people, quite possibly the most expensive first, regardless of when they joined!