Well after careful reading of the OpenGL 4.2 specs, I found that the snorm textures are not part of the required framebuffer formats. Only the color formats for “textures and renderbuffers” are required. This doesn’t include the snorm textures which are a part of the “texture-only” color formats.
Quote from section 4.4.4 of the OpenGL 4.2 specs.
Required Framebuffer Formats
Implementations must support framebuffer objects with up to MAX_COLOR_-
ATTACHMENTS color attachments, a depth attachment, and a stencil attachment.
Each color attachment may be in any of the required color formats for textures
and renderbuffers described in sections 3.9.3 and 4.4.2.
Quote from section 3.9.3 of the OpenGL 4.2 specs.
Texture and renderbuffer color formats (see section 4.4.2).
– RGBA32F, RGBA32I, RGBA32UI, RGBA16, RGBA16F, RGBA16I,
RGBA16UI, RGBA8, RGBA8I, RGBA8UI, SRGB8_ALPHA8, RGB10_A2,
RGB10_A2UI, RGB5_A1, and RGBA4.
OpenGL 4.2 (Core Profile) - August 8, 2011
3.9. TEXTURING 213
– R11F_G11F_B10F and RGB565.
– RG32F, RG32I, RG32UI, RG16, RG16F, RG16I, RG16UI, RG8, RG8I,
– R32F, R32I, R32UI, R16F, R16I, R16UI, R16, R8, R8I, and R8UI.
Hope this helps someone else too!