The thing is that the wt20 is happening in India so his performances in this series are far more relevant than the last few series everywhere else. He also is a bit of a slow starter who cashes in once set, and that hasn’t happened this series and it also doesn’t really help England’s batting style. As other people have pointed out on here, there’s also a really big gap between his domestic (33.13 avg, 128.22 SR) and t20i stats (49.21 avg, 144.61 SR), and typically you won’t see players with a sufficiently long career having such a big difference between domestic and international, especially when the international stats are better than domestic. Cricinfo even wrote a good article recently about Malan and it was interesting when they said that he typically doesn’t end up playing for England, for one reason or another, when he’s in bad form, which makes his t20i stats look better. Also look at the talent that is being kept out of the team by accommodating him: Billings and Livingstone in the squad, Banton (played in the summer), Root (played well in wt20 2016), Vince (very good BBL season), Hales (also good BBL season). In all likelihood, if Hales never got banned before WC19 then he probably would’ve been a permanent member here and Malan may never have gotten a chance in the England t20 team.