Does it bother you? If you all share meals, will you both be able to be accommodated? If it's something you do, will going out to eat be a problem? (And to be fair, most places have one or two things like chicken tenders for people that don't care for the cuisine their restaurant specializes in.)

Some people might see his diet as limiting. Some might see it as a win, "I will always know what to get him."

If he and you are open to it, you might both explore ways to help him branch out, like recreating some of the Lunchables he likes. If he likes those, see if you can mix it up a little.

Now if this guy is just not open to new things all together (aka it's not just limited to food... food aversions can't always be helped), I would be far more cautious. That says a lot more about his personality.

If the whole mess just seems like too much trouble (no judgement), I just wouldn't bother. Life is too short to be dating someone that does something fundamental you can't stand.