Tape drives will, when writing, re-read the data as it is written to make sure no errors are written and will transparently correct any errors. In addition, quite a bit of error correcting code is written, making it possible to correct simple errors.
So perhaps not 100% immune, but partial immunity to bit-rot is a pretty important part of the LTO spec.
Immune, no. Far less prone to bit rot? yeah. My source is running backups for a significant fraction of a large univiersity for ~20 years. We had a routine cadence of tape errors, which were much less frequent than our routine cadence of disk replacement.
I suppose that's anecdote. :) But it's what I've got.
Have any data to back your claim?