To be fair, I think it gets more complicated than usual if, as in some of these 'van' discussions, the power source is not (or is not necessarily) referenced to earth - since 'earthing' then effectively has two possible meanings. You are presumably thinking, as one normally would in terms of grid-supplied installations, that the purpose of 'earthing' is to facilitate operation of protective devices in the presence of faults (whereas 'bonding' is to equalise potentials) - things then are 'earthed' to the installation's 'earth', which is in turn connected to 'true earth'. I think eric is probably using 'bonding' to talk about 'earthing' in that sense - but he's probably doing so because there is not (necessarily) any connection to true earth, and thus in order to avoid confused/confusing statements such as "the CPC is earthed to the unearthed vehicle body".........................
Kind Regards, John
