The article mentions, «there will most likely have been far more than 100 deaths in nursing homes in a close temporal relationship to vaccination in the relevant time period. Our findings cannot therefore be used to estimate the incidence of vaccine-related deaths.»
This is a statistical argument. However, the experts examined the clinical histories of each of the 100 residents who died. They also had the event reports from the staff.
These data allowed the subsequent causal analysis. Causal analysis disconfirms the purely statistical argument quoted above.
The causally derived numbers therefore do instead positively allow their use to estimate the incidence of vaccine-related deaths.