The reason why Jos Butler, Alex Hales, Quinton De Kock, David Warner, etc. are star t20 batsmen aren't just because they can hit 4s and 6s, it's because when those boundaries dry up they can still score productively by proactively hitting those 1s and 2s at a good ball-by-ball rate. Although they've been in bad form this year, RizBar are very good at pinching those 1s and 2s (the problem with them being of course their PP hitting but that is another subject).
Now in regards to Sharjeel, the man play style-wise definitely is a boundary hitter. Is he going to come off hitting those big boundaries every single game? No, as that is true for all the other hard-hitting t20 batsmen of the world. That being said, what would happen if the bowlers dry up his boundaries? He would then need to rely on pinching those 1s and 2s, score at a brisk rate and wait for the bad balls. Put Sharjeel in the recently concluded MCG final. England bowlers are very much capable of drying his boundaries and if Sharjeel relies on hitting the gaps, I highly, highly doubt we'll see a lot of twos ran from him due to his fitness. There'll be more singles than twos that is for sure.
I'm not against Sharjeel playing for Pakistan but lets not act like he's on the level of Butler, Warner these days that Pakistan are keeping out. From my end, if he tears it up in the upcoming PSL then I wouldn't mind him being in future Pak t20 squads. However, the issues still remains of how he runs between the wickets when his boundaries are dried up.