In fact they had nothing to gain, but two factors should be considered. Firstly the Scottish army had been recently destroyed at Solway Firth, so Henry could have invaded Scotland if he had wished. Secondly there was a power struggle over the regency. Th Earl of Arran used the treaty to confer a kind of legitimacy over his regime, in opposition to French interests represented by th Queen Mother.
Once he was established, six months after the treaty the situation was very different. Henry was planning a new
campaign in France and halfheartedly sent raiding expeditions into Scotland, alienating the population, so that Arran felt able to tear up the treaty,