The problem with your argument here is that Giants do not level with the player. http://www.uesp.net/wiki/Skyrim:Giant So if you are at level 7, Giants are going to a lot tougher than you. By player level 50 Giants are going to be a lot weaker. The fact that you can kill a giant at level 7 with a bow has to do with the advantages of ranged combat over a Giant's relatively slow club attack. It has nothing to do with level scaling. Even if there were no level scaling in Skyrim you would have been able to kill the same Giant using the same technique just as easily. Not everything in Skyrim is level scaled. Giants are just one example of creatures that are not level scaled in Skyrim.
He would have been far better served citing Draugr bosses, since those
do level with the player and can be a tough fight throughout the game unless you optimize your character and/or play thereof. They're also vulnerable to ranged combat, for many of the same reasons that Giants are, however they do often have a ranged attack of their own with which to retaliate, which lessens the issue (considerably, in some cases).
@Hexpane:
When discussing the merits (or lack thereof) of scaling opponents, you
have to look at it from the end-game point of view, because that's where the problems arise. One of, if not the, most common complaint(s) about
Morrowind was the utter lack of challenge past about level 15-20 or so, because there was very little scaling and no high-end fixed-level encounters. They sought to rectify this in
Oblivion, but the implementation of scaling there was so ham-handed that
it became the #1 complaint instead. Now, that does
not necessarily mean that scaling is, in and of itself, a bad thing, since it enables the presentation of at least some challenge to high-level heavily-geared characters; rather, it means that
poorly-done scaling is a bad thing.
As for the ease (or lack thereof) of
Skyrim's combat, that has little or nothing to do with scaling and pretty much everything to do with the moronic, and therefore easily exploited, AI. That enemies telegraph their heavy attacks from two miles out doesn't help either, as anyone who's paying even a modicum of attention can, if they so choose, avoid ever being hit through timely dodging.
Since it seems to have been missed (again), I'll reiterate and paraphrase a previous point of mine: when debating the worth of scaling, it is important to note that even though those opponents that scale with the player may give a feeling of a lack of progression, the fact is that one
is still progressing, as is made evident through the increasing ease with which previously difficult encounters are dispatched.
It is also important to note that those who desire scaling do not wish it to be done across the board, but rather that it be done to a select group of foes that are meant to present a challenge to even the most top-end characters.