Sorry, there isn't a TIN specific API call in Pro to do this yet. Therefore, calling a GP tool is probably the way to go. Instead of Intersect3DLineWithSurface look at InterpolateShape, which will produce 3D points from your 2D query locations, or AddSurfacceInformation, which will add a height attribute to your 2D query point features.
We are evaluating TIN API requirements and are seeking input. Aside from spot height query, do you have other needs from a TIN API?
Regards, Clayton