Correct, it is a simple envelope detector and the equivalent of a toggle flipflop. The chip has an internal 100K pull up and an NPN output transistor. 38kHz bursts discharge C1 until T1 turns on and presents a positive edge to the 4017 clock input. T1 turns off at around 4.5 V, or 90% of Vcc. 95% would be three time constants (30 seconds), so how soon the circuit will respond to another button push depends on how long the last one was. After a long received pulse the circuit will not see another valid input for about 30 seconds.
There should be a 47 uF decoupling cap from pin 2 to GND.
ak