If text contains value from list then return that value

Actually, there is a mor elegant way for it:

let
    Source = #"Table 2",
    #"Added Custom" = Table.AddColumn(Source, "AllWords", each Text.Split([Message], " ")),
    #"Added Custom1" = Table.AddColumn(#"Added Custom", "KeywordFound", each List.First( List.Intersect( { [AllWords], #"Table 1"[Keyword] } ) )),
    #"Added Custom2" = Table.AddColumn(#"Added Custom1", "ContainsKeyword", each [KeywordFound] <> null)
in
    #"Added Custom2"

This assumes that you only want to find full word matches. If you're looking for Substring/partial matches, there is another solution for it in the file attached.