Because, Tomohawk is fired from a VLS
The 533mm torpedo tube limits the Babur.
Really, how so?
Among 533mm torpedoes a length of 5.5-6.5m (US/NATO) and 7-8m (Russia) is quite common. These weight respectively 1500-2000kg or 1750-2250kg. Russian 650mm torpedoes are 11m and weigh 4 tons.
Tomahawk
Diameter 20.4 in (0.5181 m)
Length Without booster: 18 ft 3 in (5.56 m)
Length With booster: 20 ft 6 in (6.25 m)
Weight Without booster 2,900 lb (1,300 kg)
Weight With booster 3,500 lb (1,600 kg)
Babur
Weight <1,500 kg (payload >300 kg)
Length 6.25 m (7 m with booster)
Diameter 0.52 m
Club 3M-14E
inertially guided land attack variant; launched from a submarine.
basic length is 6.2 m (20 ft), with a 450 kg (990 lb) warhead.
Its range is 300 km (190 mi).
It has a subsonic terminal speed of 0.8 mach.
Club 3M14K
inertial guidance land attack variant deployed by the Russian Navy. The submarine-launched weapon has
a basic length of 6.2 m (20 ft), with a 450 kg (990 lb) warhead.
range is 1,500–2,500 km (930–1,550 mi).
subsonic terminal speed is Mach 0.8.