Christian was recommending not to bond bathrooms the other day. Am I
confusing two issues here ?

Only under specific circumstances.

The basic premise of the OP is correct. It is safer to have isolated
metalwork in the bathroom than to have earth bonded. However, if there is a
chance of earth bonding by whatever means, then it is much safer to ensure
that all the metalwork agrees what that earth is by doing the supplementary
bonding.

The result of this is that if the parts are already isolated by being
connected via plastic pipework and not having an electrical connection and
not touching structural metalwork in the building, then supplementary
bonding should be omitted for that item (usually a bath or radiator) to
maintain that isolation. If, however, there is a chance that the metalwork
might be earthed in any way (via pipes or whatever), then the supplementary
bonding should be applied.

Best: Complete isolation.
OK: Supplementary bonding
Unacceptable: Extraneously earthed, but not supplementary bonded

Christian.