In coding, leadership by example and mentorship are one of the most fundamental aspects of true leadership.
In fact, if you have junior devs, the most rapid way to make them more productive, is by putting them with senior devs with good habits they can lead from.
The article is also misguided: someone with 6 months experience can literally not 'lead' someone with 20 years experience in the hierachical sense. It's completely illegitimate.
They can however, manage staffers with senior abilities, in the same way you can hire contractors to build a house. The 'contracting' relationship implies a lot of trust across the boundary, which is what will have to be the case in a 'junior leadership' role.
In fact, they probably should avoid calling it 'leadership' in any sense of the word.
He is probably the 'team bus driver / manager / stock guy' compared to the senior devs, who are like the 'players on the field'.