Does a bumpmap need to be linearized from sRGB when being read? By a bumpmap, I mean the black and white height map, not the rgb normal map style one. If I were to convert a bumpmap to a normal map then I don't think I should linearize the values because if an artist creates two pixels, one looking twice as bright to them, and therefore high, let's say at 0.2 and 0.4 values in sRGB, this is how they should be read and what the normals should be based on, right?

Converting them from sRGB to linear would mean that what looked liked two pixels with a height difference of 2 times (0.2 and 0.4) would get read as (0.03 and 0.13), if I got the calculation right.
We can not answer this question. This is important, and you need to get this info from the artist (or vice versa you need to give this info to the artist before he begins) It entirely depends on what kind of assumptions were made when the artist was working with the image.


Was the artist working by numbers
Was the artist working by eye
Was the artist working with a sculpting application
Was the data built from a photograph


You would be right if the artist worked by number. But if the artist was working by eye, which is incredibly hard, then you would be a bit off. sRGB does not entirely match human brightness sense so you should really fiddle a bit with the exponent if this was the case. But you might as well skip this. For sculpting and baking the image is most likely to be linear already to begin with, although the profile might not reflect this. And for the photograph case depends heavily on the method.

Safest bet is to do no conversion at all. But it is not really defined so strictly. Kind of the entire world of image manipulation has skipped how to tag images that arent you know display images but pure data. Who knows how it is encoded.