That's the thing: "open source" is not a movement. And ESR wouldn't be a particularly charismatic leader (he's more of a controversial one).
Open Source would never be where it is now without the Free Software movement (which is an ideological one). Maybe some corporations would still promote the OSS approach due to its economic benefits, but probably not. It likely wouldn't have the same midshare among developers that it has today.
The entryists have a response for this too: call for the removal and replacement of all the leadership of relevant organizations, as they have already done with the FSF.