可以这样理解。

1. This is to say... 这意思是说......，这意味着......

2. None of this is to say... 这都不是说......，这些都不意味着......

此外，这种表达不仅仅限于to say，如果需要，其他动词也可以。

This is to do... 这是为了......，这样做目的是......

This is to say he is a fool. 

换句话说，他是个傻瓜。

This is to help her to come to terms with her early upbringing and make sense of past experiences.  

这旨在帮助她认可自己早先所受的教育，并让她了解自己过去的经历。

But this is to begin literary culture at the wrong end.  

但是，这恰恰将文学的修养过程本末倒置。

None of this is to dismiss all the concerns of the secular opposition.  

所有这一切都不能打消世俗反对派的担忧。

None of this is to argue against broadening the range of company directors.  

这些都不是反对扩大公司董事范围的理由。

None of this is to absolve governments and regulators of responsibility for the crash.  

所有这些并不是在为政府和监管部门开脱责任。