The Leafs biggest problem was not a lack of grit overall, they had gritty players like Hyman and Simmonds. Their main problem is that their star players are not money players who can elevate their game in the PO.
And as you pointed out above, Tampa added grit to complement their smaller star forwards and it is important to point out that those guys - Coleman, Goodrowe and Marun - are third and fourth-liners. Yes, these three guys contributed as expected for role players but Tampa did not win the cup back-to-back because of these three guys. They won because their top players like Kuch, Point and Palat delivered the goods when it counted, unlike the Toronto top guns.
And the Habs have already an advantage in its roster construction - two of the top 6 forwards are 6-4, one of them being a legit power forward who is already physically dominant. Then there are interesting grit candidates for the bottom six roles already in the organization: Heinenman, Tuch and Florian X.
This management has done a great job in improving the balance of size and skill going forward and there is no reason to obsess over size.
But if they think Tij is the best prospect at that position, I have no problem with it, he brings some great qualities to the table. The only thing I don't get is why MBN is not, at least on the surface, in the conversation.