And, here's the statics analysis. Conclusion: He's very safe.

For those without Imgur:

Assumptions:

• Static coefficient of Friction (μ)=0.5

• Weight of worker=200 lbs

Force on bottom of ladder leg:

sin50°=200/a

a = 261.081 lbs

Force on wall:

tan50°=200/x

x = 167.82 lbs

Check:

261.081² = 68,163

200² + 167.82² = 68,164

Close enough.

Maximum static frictional force:

167.82 lbs*0.5 = 83.91 lbs

Conclusion:

Not only is he more stable than a free-standing ladder, but there's up to 84 lbs of lateral force preventing the ladder from being knocked to the side.

Additionally, to knock the ladder upward and dislodge it, more than 261 lbs of upwards force would have to be applied long enough to move the ladder past the edge of the floor.

EDIT He can also lean out over 3', much more than he would without the ladder leaning against the wall.

Statics

How far over can the worker lean?

Assumptions:

• Elevation of worker above upper floor=8 ft

• Weight of worker=200 lbs

• Maximum static frictional force = 83.91 lbs (Calculated previously)

(Weight of worker)/(Lateral frictional force)=(Vertical distance)/(Horizontal distance)

(200 lbs)/(83.91 lbs)=(8 ft)/x

x = 3.36 ft

Therefore, if the worker's center of gravity is 8' above the floor, he will be able to lean out well over 3' from the edge of the ladder. (This neglects torsional forces from leaning out, which is reasonable, as the railing is keeping the ladder from twisting.)

source