The 'anti-pipeliners' seem to be divided into two groups, the first group is against anything and everything to do with the expansion of the fossil fuel industry. Those people have to be told flat out ... "fossil fuels are here to stay for decades to come. Canada either takes advantage of our natural resources, responsibly, and exports more to the world; or we keep those resources in the ground and let other countries, like our neighbour to the south, wave good-bye to us as our economy tanks. Your argument is not relevant or sustainable in today's global environment."
The second group appear not to be concerned with pipelines as much as the increase in 'diluted bitumen' through the expanded pipeline, and the increase in tanker traffic to transport that bitumen from Burnaby to elsewhere. In their minds, there is a greater risk for an accident or spill which is I will say, is possible. If there is a spill, they don't believe that bitumen can be recovered or the water cleaned, the same as other types of oil. Even though the NEB and other environmental studies took all of that heightened risk into consideration when the expansion was approved .... that does not seem to be good enough. This particular group (Horgan included) of anti-pipeliners seem to think they know more about risk.
If decisions were based solely on risk ... nothing would get built. There is always the possibility of something going wrong but that is why you take appropriate precautions. For example, trains loaded with highly explosive fuels and chemicals roll through downtown Calgary dozens of times every day. The frequency would suggest there is a high possibility that something could happen over time. Does that mean no one should work or live in buildings nearby .......as there is risk of a derailment and possibly an explosion? The precautions taken to prevent something like this happening in a highly populated area, makes the probability of that happening as very low.
The same argument and logic applies to pipelines or refineries or LNG plants or anything else people want to protest against.