The problem is, Leeloo, 75% of stammering in under 5's resolves naturally anyway or goes away only to resurface and the evidence that's most robust for Lidcombe is in this population. The prevalence of confirmed stammering in adults is somewhere in the region of 1-2%. So, for me, it's not about not doing something that is quick and easy and will fix a lifelong problem, it's about whether in our specific case, we are dealing with an actual current problem or a slight possibility of a future problem. There is a world of difference in solving an actual problem as opposed to a hypothetical problem.
The research currently can't tell us who will go on to be in that 1-2% and who won't, so the ethics of 'do something now' and 'do nothing now' is not always clear, and differs based on case to case, on all sorts of variables. This is why I do think it's important to have an assessment, and it sounds in this case, this little boy's needs have been assessed differently according to two different therapists, which sort of reflects that this isn't always clear cut.
I have to say my boy had a much more severe stammer at 2-3 which involved far more frequent syllable repetitions and some other disruptions, and since then it has followed a pattern of emerging at times of language shift (when he's moving up a level with talking) and then just going. As he is in school now, it is more likely - but not definite by any means, especially under seven - that it will hang around, but essentially he is stammering without struggle or is what some call a 'fluent stammerer' and it tends to be only when he's very tired or excited that it's really obvious to others.
I have obviously employed a wide variety of strategies to support this with a goal and value of making communication enjoyable for him, so though he's had no formal intervention, I'm aware he also hasn't exactly had the same experience as someone else who maybe doesn't come to parenting a child who stammers with a lot of experience of and knowledge of stammering, especially as parental understanding of stammering is such a large part of intervention. Also, my thinking is entirely based on his current presentation, and I've obviously had fluency formulations done by some colleagues who specialise in stammering (my specialist area is autism and language impairment, though I'm obviously qualified to intervene with stammering too).
It comes down to this: whose problem is it? Right now, it's not a problem for us, it's not a problem for him.. So intervening would be to prevent it being a problem for others in case this then becomes a problem for him.. Which to my mind, is like insisting on contacts for young children as glasses will make you get bullied or dying ginger hair.