ScriptSig in P2SH-P2WPKH BIP16
For node &gt; 0.13 is it a trigger the say to node, Hey, I'm a segwit transaction! check in Txinwitness!
For node &lt; 0.13 Push ScriptSig inside and that's it, the transaction is ANYONE_CAN_SPEND

Almost exactly right.
Segwit validation code was added in Bitcoin Core 0.13.0, but mainnet activation logic was only added in 0.13.1. That means that 0.13.0 will not enforce these things on mainnet yet (and 0.13.1 will only do it for the part of the blockchain after block 477120).