Sorry your dog died :(
What he said perhaps wasn't exactly direct, but "less than a million years old" references using cellulose for fuel not coal. Yes coal of any kind isn't going to be carbon neutral as the time frame is too long.
Using actual plants, whether tree/sawdust, shrubs, switchgrass, etc is still orders of magnitude better for the environment since you're using carbon removed from the atmosphere extremely recently and from sources that we, conceivably, could renew.
The scale needed for that is significant and possibly not practical, but as the poster was saying, IF, we can get cheap cellulose to fuel it raises a significant option in the goal of carbon neutral energy sources.