Sudoku Solver .. by logic

Unable to complete puzzle # 22 in Second-Degree Black Belt Sudoku, I turned to http://www.sudokusolver.co.uk which is able to:

• use Guess-and-Check soduku solving steps
  
• determine whether a sudoku puzzle has a unique solution

Using this website, puzzle #22 is found to have a unique solution, but is not solved using my paper and pencil logic. Naughty!  Do Guess-and-Check style soduku puzzles represent a logical puzzle?  Perhaps yes if you are a computer.