The reason it doesn't pick it up as an issue is that currently, that format is still permitted. In SQL 2016, 'string_alias' = expression will be accepted, however, it will not be in a future version of SQL.

The same is true for not ending with Semi Colons, It is still permitted in SQL 2016. Deprecated means that it is going to be phased out and removed, not that the functionality has been removed already.

The tool is most likely going to bring back breaking changes,  of which details can be found here: https://msdn.microsoft.com/en-us/library/ms143179.aspx