Camera colour space is sRGB.
Its an issue ive had going back a few years with various canon compact and DSLRs and all versions of LR/ACR at the time.
Rebuilding the red channel would be a lot of work - its easier to import raw into DPP then export the TIFF into lightroom. Its an extra step and one id rather not make hence the question.
I can edit that TIFF perfectly.