How to understand the weird logic?

How to make your house secure? How about this: Secured by a withe twisted in the handle of the door, and stakes set against the window shutters; so that, though a thief might get in with perfect ease, he would find some embarrassment in getting out?

So that? It seems to me that a thief can easily get in and easily get out. How can the thief will find some some embarrassment in getting out? Is it because he will get out empty-handed? Or bewitched by some spell?

Context:

His school-house was a low building of one large room, rudely constructed of logs; the windows partly glazed, and partly patched with leaves of old copy-books. It was most ingeniously secured at vacant hours, by a withe twisted in the handle of the door, and stakes set against the window shutters; so that, though a thief might get in with perfect ease, he would find some embarrassment in getting out; an idea most probably borrowed by the architect, Yost Van Houten, from the mystery of an eel-pot. The school-house stood in a rather lonely but pleasant situation, just at the foot of a woody hill, with a brook running close by, and a formidable birch tree growing at one end of it. From hence the low murmur of his pupils' voices, conning over their lessons, might be heard of a drowsy summer's day, like the hum of a beehive; interrupted now and then by the authoritative voice of the master, in the tone of menace or command; or, peradventure, by the appalling sound of the birch, as he urged some tardy loiterer along the flowery path of knowledge. Truth to say, he was a conscientious man, and ever bore in mind the golden maxim, "Spare the rod and spoil the child."- Ichabod Crane's scholars certainly were not spoiled.

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http://www.castleofspirits.com/sleepyh1.html