Basically, yes. The agreement is reciprocal which means that VA elites get access to DL Skyclubs, and DL elites get access to VA operated lounges only. Of course, as a DL elite you still get access to Skyclubs where available, even when flying VA. So in SEA, you are flying DL to LAX and connecting internationally on the same ticket (or same day on a partner). You'd always have club access as a GM.

This is a nice partnership as it even includes access for domestic flights within Australia. The downside is VA doesn't currently operate any international lounges (set to open one in WLG soon). So, that means at many international ports, DL elites flying VA are out of luck, unless they can access a Skyclub. So for LAX, your only option is the Skyclub, not the Emirates lounge which VA elites get access to.

VA has started a new lounge contract in SYD, BNE, & MEL on the international side in conjunction with No1 Lounges. I don't believe it changes the DL elite situation, but it might be worth asking on your return journey. Please post your experience!