I get very suspicious if a paper samples multiple groups and still uses p. You would use q in that case, and the fact that they didn’t suggests that nothing came up positive.
Still, in my opinion it’s generally OK if they only use the screen as a starting point and do follow-up experiments afterwards
Science is like going down a Wikipedia rabbit hole. There’s always more things to do and more things to check out. At some point you just have to draw the line and say that enough is enough. Other scientists are likely to ask why you stopped where you stopped, and so saying that “it’s outside the scope of the paper” is basically the nice way of saying that you stopped because you felt like it