People should totally be multi-modal on the canal. I absolutely hate cyclists when I'm running on the towpath (and I'm slightly more tolerant of out of control dogs).
I can well imagine that if you just want to grab the pram and meander around with a toddler off the reins then cyclists are a real barrier. I'd be interested to know whether people think uncontrolled dogs are worse or not.
At least you know that cyclists will be trying extremely hard not to end up in A&E (regardless of the social stigma of running down a toddler) but this isn't true of some of the slavvering monsters that are cut loose on the towpath. Then again, you don't exactly hear of many dog attacks (even fewer than cyclist attacks?)
Positioning the issue as one of cyclist behaviour is a non-starter either way. The best way to frame the debate would be to see issues on the towpath as transferred violence from drivers (at the top of the food chain) to the people lowest down, and in fairness that's sort of what's going on here.