The Canadian Championships were being held at the exact same time... which are used to select the team for the Worlds. However, some of Canada's top athletes competed in DR.
Looking at the results from 2015, its reasonable to expect three medals for Canada in Lima, even with the reduced team (13 in 2015 vs 4 in 2019). Darsigny, Santavy and Charron all would have won medals in Toronto 2015 with their pb's and by quite a distance at that, so something similar could happen in Lima.
----
It also comes down to funding. For the CWG's all or most of the weightlifters were ranked in the top 5 (ie fully funded travel). For Pan Ams only the top 2 in each gender (and they must also have 95% of the world champions total) to be funded.