In "The Metamorphosis," when Gregor's father pushes him back into his room at the end of section 1, why is it called "a true deliverance"?

It is "a true deliverance" in several senses, firstly,
because both Gregor and his father want Gregor to be back in his room. Secondly, and
perhaps most importantly, it is because Gregor finds himself in a very compromising
situation as he is actually stuck and cannot go anywhere and thus is forced to have his
wounded flank exposed to the anger and violence of his father. Note what the text tells
us:

With one
side of his body heaving up, he sprawled lopsided in the opening. His one flank was
bruised raw, ugly splotches remained on the white door, and he was soon wedged in and
unable to budge on his own. The tiny legs on his one side were dangling and trembling in
midair and the tiny legs on his other side were painfully crushed against the
floor.

Thus it is that Gregor
is trapped and finds that he cannot move. His room to him represents his shelter and
home, a place of safety, as his father does not enter there. To be trapped in such an
exposed position is incredibly dangerous for him. Thus it is a "true deliverance" when
his father shoves him strongly enough to put him back in his
room.