Boeing, Dassault have always designed aircraft with Catapult assisted launch , not STOL variant , all their fighters have been twin Engined with effective thrust for that Take-off.
In case of N-LCA , it was similar to F35b version with STOVL variant and landing and L.M had experience of both F35 and LCA bcoz-----
L.M was initial consultant in Tejas programe in 90's . our FBW was initially tested and certified by L.M testing center . So it was logical to go with them initially
First of all, not all Dassault carrier fighters was twin engine fighters:
Dassault-Breguet Super Étendard - Wikipedia, the free encyclopedia
Secondly, the important point of making a fighter carrier capable is not the way it starts, because for catapult starts you just need to make some changes at the front gear and ski-jump take offs needs just a good T/W ratio. The key here is the strenghtening of the airframe and the gears for the arrested landings, because that will make the biggest difference for LCA in IAF, or on IN carriers.
So for this Dassault, Mig and Boeing are clearly more experienced than anybody else!
Also you count the experience of LM with F35B, but what experience do they really have with it? That aircraft is not operational, it is just in testing stage and did only some vertical take offs and landings at land. AFAIK there was not a single carrier landing so far, which would surprise me anyway, because they are delayed in the development too and have enough other problems.
So to me, they don't really have experience in making a fighter carrier capable!
The most logical choice would have been the Russians, because we use their carrier design and even their Mig 29Ks, even the French would make more sense, because they was involved for the overall design, which should help them to make changes for the use on carriers. LM is really the last that I would think about if I was HAL.