Wow, this idea hurts my head. I dunno how it would work, but it's certainly a fascinating idea to consider.
The thing to consider, though, is the "rubber band effect" that brought everyone back into mosquito morph at the end of book #18. So even if Tobias's extruded mass were found, it would only be a temporary "rescue," before the stretched rubber band would take him right back to the time, place, and body where he was before. Perhaps there's some theoretical way to make the other body permanent, but I have no idea what that would be.
And I'd like to note that it's also been theorized that morph mass disappears after two hours (I believe some have speculated that that is the entire reason why people can get trapped in morph in the first place). If that's the case, then this idea obviously wouldn't work, because it would mean that Tobias's original morph mass would be long gone.
And another thing to point out. Obviously, Tobias's morph mass from morphing the mosquito in #18 was kept separate from any morph mass that would have been left from the first time he morphed a hawk (shown by the fact that he appeared as a hawk in Z-space in that book). So what would happen if you happened across his hawk-mass while he was morphed into something smaller, and rescued him then? His matter might wind up strewn all over the universe, and he'd rubber-band back to hawk, then rubber-band again back to whatever he'd morphed.
Oh lord, my head . . .