The Artscroll siddurim (that I've seen, I haven't done a full survey of the siddurim and machzorim) translate the last line of Yetziv Pitgam as a reference to Yonatan ben Uziel.
The Artscroll chumash, on the other hand, translates it differently, as a reference to Hashem, Who gave (יהו-נתן) the Torah to Moshe (גבר ענותן).
Since Yetziv Pitgam is an introduction to the targum on the haftara, it's pretty clear that the first interpretation is the simple understanding. What is the earliest source for the Artscroll chumash's more creative reading? Is there any evidence that the paytan intended the double meaning?