Intelligent life could evolve frequently, even within their model, if you consider panspermia (life transmission via rocks between star systems). The infrequent evolutionary events just have to happen once, then get spread all over the place, in the bodies of something like an alien-Tardigrade. Moreover, life could exist off planet. Here is a presentation by Freeman Dyson talking about searching for life in the Kuiper belt (where all the real estate is):

https://www.ted.com/talks/freeman_dyson_let_s_look_for_life_...