Actually, as soon as Rocky had made his identity known, Old Jack and Lin Feng had already anticipated the suggestion he might make, so when he finally voiced it, neither of them showed much surprise; instead, they both fell into silence.
This reaction was certainly a good sign for Rocky since their hesitation to immediately refuse meant they were considering it.
In fact, this was indeed the case; Old Jack and Lin Feng were seriously considering Rocky's suggestion, not because it was particularly good but because Backhill Village had very few options left.
If they disregarded Rocky, then Backhill Village would inevitably face the next wave of attacks from the demons, and no matter how quickly the village tried to repair or even hire other mercenary groups to help, nothing could guarantee the village's survival from the next wave of demon attacks.