Ya, the razor you linked says the blade is Z-Finit steel, not titanium alloy.
Grade 4 is unalloyed, "pure" titanium, it's not an alloy like grade 5. Alloyed titanium has way different properties than CP (commercially pure) titanium. It's like comparing pure iron with steel. Just a little tiny bit of carbon completely alters the properties of the iron and makes it heat-treatable steel.
Grade 5 is roughly 6% aluminum and 4% vanadium, with the remaining 90% being the titanium base metal, hence the alloy is called 6al4v. The 4% of vanadium is a "beta stabilizer" that lets the metal take on different crystalline structures (beta phase) other than the natural close-packed hexagonal of pure ti, so it can be heat-treated and work-hardened to some degree, and it's mechanical properties are altered. The 6% aluminum is an "alpha stabilizer" that makes the alloy tend to skew back towards natural HCP, and protecting it from taking on too much beta phase effect.
If a titanium blade was to be improved by cryo treatment, it would most likely be seen in beta titanium, the fully heat-treatable types that can take on a slew of different crystal grain structures. Not sure how good it would be as a straight razor.
Grade 5 titanium would make a great hatchet or 'hawk, and would improve with use as it work-hardens. Even better if the blade edge is forged.
