Zelena definitely could get information out of Rumple, but it just doesn’t compute for me that she’d send Walsh to keep Emma away from SB, and then send Hook to bring Emma back to SB. She’d have to have had a complete 180 change in motives, and Walsh would have had to be completely unaware of that change, and I’m thinking he’s remained in contact with Zelena somehow to let her know that their plan to keep Emma away was still on track, so he should have known if plans had changed so drastically.
If the WW was watching Walsh and Emma, she would see how hesitant Emma was in accepting Walsh AND she’d see a certain Pirate leave and exist the restaurant. She would then tell Walsh to up his game before Hook managed to convince Emma to do anything.