ML uses almost entirely applied math and stochastics: optimization, numerics and statistics.
Besides that, just because they won't have faculty researching pure math, doesn't mean they cannot have applied math guys teaching pure math classes.
Personally as a math graduate, I think it is better that they focus on areas they are good at. I assume the pure math department is not doing much. It is also good for the students who might want to study math and end up at studying at a university that does not do pure math very well.