Emphasis on "likely" - the authors do not conclude with any certainty, they're speculating based on the available evidence, just like you.

I guess your personal threshold for "plenty of reason to conclude" is lower than mine, and that's okay - to each their own.

But it's very clearly spelled out in the sources I cited: currently there is limited evidence demonstrating the safety and benefit profiles needed to conclude that every child and every pregnant woman should be vaccinated.