Ambarkanta

[ArcusCalion]

Tolkien explicitly says an intervention of Eru would be necessary for that reading, and then declines to ever give that reading credence. It seems untenable to assume it when he did not take the explicit chance to confirm it, rather treating it as unlikely. Basically he's saying 'that scenario would take a miracle.' Which is to say - it is unlikely to be the case.

As to the reading of the footnote I am genuinely unsure how your interpretation can be taken from his words. Taken as a continuous text, with the footnote absorbed into the main flow, it reads:

That should mean that he was put outside Time and Space, outside Eä altogether; but if that were so this would imply a direct intervention of Eru (with or without supplication of the Valar). It may however refer inaccurately to the extrusion or flight of his spirit from Arda, since the minds of Men (and even of the Elves) were inclined to confuse the 'Void', as a conception of the state of Not-being, outside Creation or Eä, with the conception of vast spaces within Eä, especially those conceived to lie all about the enisled 'Kingdom of Arda' (which we should probably call the Solar System).

he says the direct words SHOULD mean that he was thrust from Ea entirely, BUT that this would require a miracle (for which he implies there is no evidence) and thus it MAY refer INACCURATELY to his thrusting from Arda into the wider spaces of Ea SINCE Men were inclined to conflate the two in casual speech and concept.

I see no way in which this can mean he is implying that Men are claiming he is sent to space. His whole contention is that the 'texts' of the lore itself was a Mannish tradition, thus he uses the Mannish misconceptions to solve apparent contradictions in cosmology and science, such as this one.