Is a Casascius coin Bitcoin? A paper wallet? If I give you a casacius coin, have I given your Bitcoin? Lightning is analogous to being able to fractionally trade a Casacius coin.
Giving someone a casacius coin is not the same as sending someone a digital Bitcoin, as the properties are different. And in the same way sending someone Lightning Bitcoin is different as it hasn't been recorded on the blockchain yet.
https://github.com/lnbook/lnbook/blob/ece69d5c2ac8116ef83c18...
That's not a very useful distinction. The latest channel update, being just a standard Bitcoin transaction, can be published on-chain any time a participant desires.
Would you similarly claim that 0-conf transactions in the mempool are not Bitcoin, as they are not recorded yet?
It’s just trading balances. Don’t fear it!