I fully agree (with both of you) that you can trade 2 Edge in order to give 1 Edge to someone else at any time. This seem to be what the "Give ally 1 Edge" is designed for. This seem to be intended.
I am not fully convinced that you can, instead of trading 2 Edge for 1 Edge, spend your Edge directly on "Reroll one dice", "Add 1 to a single die roll", "Reroll all failed dice", "2s count for glitches for target", "Create special effect" etc in a test where you are not the actor nor the opposer. To me this seem to be twice as effective as spending Edge to Give Edge to your ally that is an actual actor or an actual opposer in the test. If you are allowed to directly spend your Edge on tests you are not involved in then you kinda undermine many of the use cases where trading 2 Edge in order to give 1 Edge away to your ally.
Having said that I can also fully understand the point that you are making SSDR (and with a strict reading of RAW I can see support for this as well as, unlike many other Boosts, the Boosts I listed doesn't explicitly mention 'your' test or a test that 'you' are involved in).
I am just not fully sure I agree to this. If you wish to use your superior tactical advantage to help out your ally in a test you yourself are not involved in there is already an existing mechanic in place ("Give ally 1 Edge").
(but I am also not fully sure I disagree)