Well, he's not human.
Why it is hard sci-fi
A long-running series built around a network of stargates that link planetside locations across the galaxy. The show is procedurally rigorous about the gate. It is a one-way passage at a time, requires a powered destination address, and the wormhole is a fixed-energy event with a working duration. SG-1 is a uniformed military team running first-contact missions on a budget, with after-action reports.
Science inside it
Stable wormhole transit through a fixed-network of gates, naquadah as a high-density power material, archaeological field methods applied to off-world sites, and a working Earth-government program with funding fights and inter-service politics. The shows Goa uld biology is consistent across seasons and is treated as a parasitic life cycle.