The summary doesn't imply anything. It just says goh has a plan. It doesn't say what he has a plan for, whether it be capturing flygon or dealing with the chaos its sand tomb is causing. Its still too early to assume anything out of the summary has we havent got a full translation yet
Ash isn't the one to steal a capture from someone who has put more effort in (Unlike Go). So Goh has higher chances in getting the Flygon than Ash is. Obviously, it can still remain a wild one, but the summary doesn't imply Ash getting it at all and leans more towards Goh than Ash. Thats why the summary implies Goh getting it instead of Ash.