Can a delta wing fighter engage an arrestor net without its main landing gear?
In August 2009, a Saab Gripen pilot forgot to extend the landing gear, and walked away from the landing unharmed. And this was without any preparation of any kind.

There is no reason to eject from a perfectly good airplane just because you can't extend the landing gear. Belly landings are a pretty "routine emergency" (if that term makes sense).

The metal scraping across the runway will probably generate as much if not more friction than the tires would, so the risk of a runway overshoot is rather negligible, and there is no need to use any arresting gear at the end of the runway.

What could make sense, though, is to use arresting gear at the beginning of the runway, if the aircraft is equipped with an arresting hook and the runway is equipped with arresting wires.

It might make sense to drop the drop tanks if they are full.

The delta wing does not play a role here, this applies more or less to all kinds of wing planforms.