I think by low level he means under six

loosing a lvl 10 cap is like getting an arm or a leg lopped off at an inopportune moment.

loosing 2 lvl 10 caps is like coming 5 hours late to work when your boss is waiting for you, because you were probed by an alien with a powerdrill.

loosing more than 2 lvl 10 caps is like waking up one day to realize the last 50 years of a happy, fulfilled life was actually a dream. In reality, you're broke, impotent, live in a cardboard box and everyone hates you and wants you to drop dead.

What I don't really understand about Caps is why it's so expensive to upgrade the next lvl of Cap ship command. All those researches are twice as expensive as normal research of similar level. Why? You also have to pay for the ship itself and the upkeep it needs. It's not like making these upgrades less expensive is going to cause enormous capital spam. Ok, maybe it's fair to make the first 2 upgrades a bit expensive, because cranking out 2 caps right from the start may be a bit much. But later in the game it's not much of an issue, I think.

An yes, I do think we need a better alternative to level Capitals later in the game. Maybe just a research that makes buying levels cheaper and faster? The Advent already sort of solve this problem, though. How about a Starbase upgrade that constantly gives experience to nearby capitals? Like a training ground or something.