It looks like the curve is flattering, and the current state actually looks slightly cherry picked (it matches a previous spike that looks a bit of an outlier before the result went down). The longer they train, the more they risk getting scooped by another release by someone else. Etc etc it's a judgement call based on all of these factors (and more, including cost/occupying a big cluster as you mention)
+1 at some point, you need to expect to train a much better base model using everything you've learnt. At the least, you probably want to bring on line the next 10 clever RL environments and ideas your team has been cooking up (which will pipeline into v2.7 etc.)
