Why didn't endurance burn from the heat generated by the accretion disk around Gargantua?

Question

We know when Dr Mann failed the docking procedure and Cooper and TARS try to dock on the spinning endurance by matching their rotational speed, the ship started entering the stratosphere to which Amelia Brand says "She's got no heat shields". Then Cooper tries to slingshot Endurance around Gargantua in one last effort by detaching TARS and himself towards the black hole just shy of the horizon, thereby giving Brand enough thrust to leave Gargantua's orbit. If Endurance was not built to withstand the heat generated while entering a planet's atmosphere, how was it able to withstand the heat generated by one of the hottest things in the universe? Accretion disks are believed to radiate in the X-ray part of the spectrum, which puts their temperature between 300,000K to 300,000,000K.

Here's the conversation:

CASE: It's not possible.
COOPER: No... it's necessary.
CASE: Endurance is hitting stratosphere!
AMELIA: She's got no heat shield.

Answer 1

This seems to be something like a plot-hole, but in fact it is a important plot element:

The builders of the wormhole WANTED Cooper to enter through the event horizon and since they can already manipulate physics enough to create wormholes, or time-travelling tesseract, it is not hard to stretch the imagination, that they also somehow cooled down the accretion disc.

Everyone (including Cooper) expects to burn within the disc - it didn't happen. Everyone expects Cooper to die/stay forever inside the Gargantua - it didn't happen. Hence this is a plot element - someone made it possible for him to survive inside of the black hole also made for him to survive the entry.

On the side note - the bigger the black hole, the cooler is the accretion disc.