Cryomancer is probably tournament viable. He can kill if he opens up an opponent 3 times, but so can a lot of other characters.
Cryomancer is /not/ a mix up variation, and hammer should not typically be used as such as both versions are highly reactable. His strength is his indiscriminate damage in relation to screen position, and how fast he paces the match with short, damaging combos resetting to true neutral (cold blooded string is essential). Neutral becomes a strength when the player knows both SZ as well as the opponents options. Well placed d4 leads to frame trap b12, and that leads to damage. This is gospel for Cryomancer players.
He has a unique meter management meta where SZ can forgo ex crushing hammer for ice ball, converting comparable damage conversions until the opponent uses a breaker, and then go in for max damage hammer combos when there's no fear of losing a precious bar to a breaker. Ie, ex crushing hammer should be gated behind your opponents abundance of meter.
His ability to counter zone, with ice ball trades or ex ice blast beating zoning completely, makes him dangerous from all ranges. In matches where clone is borderline useless (Special Forces Sonya), rush down may be more of an asset than clone meta.
It'd be an uphill battle, but a testament to skill if you can do it successfully. The issue is he does many things well, but too many characters do what he can, only objectively better.