Dey, comparing a LST with a carrier is like comparing a Mazda
with a 3 tonner. I would've expected a self proclaimed knowledgable
person like you to know better than make this kind of silly
comparison. 
The size of Jurong shipyard is not the issue. Even if it was large
enough, the fact is ST Shipbuilding lacks the funds & expertise
to make a carrier.
It is neither affordable nor practical for RSN to have an aircraft
carrier. Should the day come that we can afford a carrier, the
money would be better spent on other things, such as replacing our
aging fleet of MGBs or PVs.
And LST is a landing ship tank as the acronym implies. You load a
few ground vehicles into it, sail to somewhere, off load these
ground vehicles. That's about it. Since its reasonably large, it
can accommodate 2 copters for either SAR or anti-submarine
purposes. That's about it.
A LST is NOT meant for accommodating jets or other fanciful thing
that you have in your imagination. If we wanted something for
accommodating jets, we would've bought over Thailand's white
elephant of an aircraft carrier, which is currently sitting in the
docks rusting away as they can't afford to send it out to
sea.
