Yes you can put boiling water in silicone.
Most silicone dishes or cups can handle up to 500 F temperature.
The temperature of boiling water is around 212 F so the Silicone should be able to easily withstand the temperature of the boiling water.
I've used silicone bowls and silicone cups with boiling water and although the silicone got softer and more flexible it did no harm to the silicone cups and bowls.
So yes you can put boiling water in silicone cups or bowls.