You can certainly think what you want and rationalize all you want about why the Saints lost. Anything I say won't change your mind about that. However your view assumes that they would have scored from the spot of the foul. That was certainly a key moment in the game but the Saints should not have put themselves in that position and anything that would or could have happened if the refs called the penalty is pure speculation. They blew the Rams out earlier in the season. They lost in their house. It hurts, I know. Always next season!
What this, unfortunately, reminds me of is when I gave a test and misspelled a word and there would always be some student who would like to proclaim "Now you have to give us all A's".