That's something I've been wondering myself. When he was Sentinel, Alan overcame his weakness to wood due to his strengthened connection to the Starheart. As of now, Alan recently tamed and reabsorbed an even greater portion of the Starheart than before, so, by all rights, he should be at least as powerful as he was when he was Sentinel. And in Brightest Day, during a brief cameo, I saw a panel of Alan lifting palm trees by a beach, which suggest that Alan can effect and is no longer hindered by wood.
Loki's savvy and versatility would make this fight last a good deal, but ultimately Scott would overpower him in the end.