I searched various datasheets, but I didn't find the information of a max discharge current for the NE555.
The maximum source/sink for the output is mentioned, but not the max sinked by the discharge pin.
I guess it isn't designed to be (ab)used this way, but having an open collector output is very handy sometimes. Specially as it enables the output pin to be used as feedback.
So, what could be the max sink current of the NE555 discharge pin?
Update: Markus mentioned in the comments that it is obvious, and after looking closely at the datasheet, even from ST, it is always about the output pin :
the output structure can source or sink up to 200 mA. ... Iout Output current (sink & source) ±225 mA
But nothing specific about the DISCHARGE pin. The only mention is a low voltage value to some current. Which I guess is for ensuring a pull down strong enough to go beyond the trigger threshold.