Fabbri is too risky for another team to give up something that would help the Blues. As it has been stated, it makes the most sense to just roll the dice and see how he comes back after an entire year off. Sadly, he looked good last year coming into camp, but he fell into that 3% who's surgery explodes and have to have it fixed again. If he comes back to form, then he'll be right back into the top 6. If he crashes and burns, the Blues are out that position and can address it through either a trade of assets or internally replaced.
Probably right now, his value to other teams who would be taking a risk is a 1 year rental or a pick and a salary dump. Since the Blues probably won't be set for a competitive run, that wouldn't make sense from an asset management standpoint.