Put it in a different lens, the employees who are temporarily laid off can access EI. The striking employees have no pay during the strike. Employers are not allowed to hire others during the temporary layoff.
What the Canada Post indicates is CP can stop operations for a quite of time ( pertinent to ESA Ontario, temporary layoff can be 13 weeks within a 20-week period or up to 35 weeks within a 52-week period), Can striking workers not pay their mortgages for that long without the power sale?