It also says "We also separately trained the initial creep block using traditional RL techniques." I have no idea how significant that is, but it seems to be getting a fair amount of attention.
(1) Not creepblocking at all, and letting your opponent have your creeps under their tower
(2) Modest creepblocking to punish (1)
(3) Severe creepblocking to punish (2)
Would be better than some hand-trained RL creepblocking which is divorced from game outcomes.