When performing a non-DNA digivolution, only the “Place 1 yellow or purple Digimon card from your trash on top of your security stack face down” part of the effect activates. The part of the effect that reads, “you may search your security stack for 1 level 5 or lower Digimon card and play it without paying its memory cost” only activates when DNA digivolving. “Then, shuffle your security stack” activates no matter what kind of digivolution you perform.