Couple of Differences in circumstances between Draisaitl and Drouin. 1) Oilers have cap space to sign Drai and TB does not have cap space considering who else they have to re sign. 2) Drai probably likes playing with the Oilers and Drouin has not been treated too well by Tampa.
Its up to Drouin and his agent to seek an offer sheet deal. If he approaches the Habs, I would be listening if I was MB (and I'm sure any GM will). Especially with the Cap situation in Tampa. Where there is smoke, there is fire. MB should be worried about future "back lash" down the road if he signs an offer sheet with Drouin but at this point, the Habs have nothing to worry about for years to come. Especially Tampa where they will be up against the cap for many seasons with that young core they have
If Bergy did offer sheet Drouin and he came on board,Steve Y would be gunning for the Habs when we sign Chucky or another player even years later.So that is something to keep in mind ,also other GMs might get a distaste for that practice.