While I don't think it's a huge problem to do the pre-flight request, this all seems technically guaranteed to be pointless for the thing you intended it. See bug 1572418 comment 34. Since you wrote that bug 1572418 made a huge difference in Owl uptake, I'd suggest you look at the timeline here: bug 1572418 landed the same time as bug 1592258. Coincidence? I think any jury would have the verdict pretty quickly on which one of them is the probable cause for the spike in Owl installs.
Bug 1594366 Comment 14 Edit History
Note: The actual edited comment in the bug view page will always show the original commenter’s name and original timestamp.
While I don't think it's a huge problem to do the pre-flight request, this all seems technically guaranteed to be pointless for the thing you intended it. See bug 1572418 comment 34. Since you wrote that bug 1572418 made a huge difference in Owl uptake, I'd suggest you look at the timeline here: bug 1572418 landed the same time as bug 1571772. Coincidence? I think any jury would have the verdict pretty quickly on which one of them is the probable cause for the spike in Owl installs.