Search a column for a certain string and return true or false

Replace the space with a pipe  "|"  and use PATH functions.

TF = 
var p = SUBSTITUTE([Where Used]," ","|")
var g = ADDCOLUMNS(GENERATESERIES(1,PATHLENGTH(p)),"f",if(left(PATHITEM(p,[Value]),1)="X",0,1))
return sumx(g,[f])=0

or if you want it in Power Query 

let
  Source = Table.FromRows(
    Json.Document(
      Binary.Decompress(
        Binary.FromText(
          "JcwxDsAgDAPAr0SZQcJO6APapQs7AvH/bxTSjPY5cyrKnUFzTdpQUKSRXqWDNF3pgCfD6xVgnzSvbgcYZcQ0GN5MGDc7lf8fpEe21gc=", 
          BinaryEncoding.Base64
        ), 
        Compression.Deflate
      )
    ), 
    let
      _t = ((type nullable text) meta [Serialized.Text = true])
    in
      type table [#"Component ID" = _t, #"Where Used" = _t]
  ), 
  #"Added Custom" = Table.AddColumn(
    Source, 
    "T/F", 
    each List.Distinct(List.Transform(Text.Split([Where Used], " "), each Text.Start(_, 1))) = {"X"}
  )
in
  #"Added Custom"

How to use this code: Create a new Blank Query. Click on "Advanced Editor". Replace the code in the window with the code provided here. Click "Done". Once you examined the code, replace the Source step with your own source.