I believe that odor will fade away eventually. Here's one blurb I found online:

Seagrass fiber is woven onto latex-backed floor coverings as a simple (half panama) or basket-weave pattern. Seagrass retains the grassy, hay-like scent and coloring of the plant from which it is extracted. However, once the rug is unrolled and installed the odor dissipates over time.

The best way to get rid of smells is sunlight. If you could take it outside on a patio in full sun for a few hours it would probably help the smell leave quicker. Although if it is room size, that may be difficult.

My mom bought a house that had been lived in by smokers and she left little bowls of vinegar all around the house. It really seemed to somehow draw out the smell (even out of the carpets).

I just bought a sisal rug. It had no smell but the rug pad I bought was off gassing like crazy. I wished I had left if outside for a few days, but by the time I realized it smelled bad I already had moved the rug and furniture back on top it. It took about a week for the smell to go away. Hopefully, you won't have to wait long for your smell to dissipate.
Good luck.