I think you should assuage most of their concerns. If they are simply pretexting, pretending to be persons they're not or using fraud or false pretences to obtain information for the purposes of the investigation, they're simply amassing the information to report to their client or whomever. They then won't be covered by the offences because they won't have the further criminal purpose of using that information to commit fraud or impersonation.
Are there occasions when they might use the information they obtain to then go on to commit fraud or impersonation? I can't comment on whether or not it would ever be something they would engage in during the course of the investigation, but I would hope not.
It is somewhat different for the police. There may still be occasions in which the police will gain information through false pretenses, and as part of undercover investigations, the information might be used in that fashion. The amendments would certainly narrow the difficulties it would create for police. The subsection 25(1) law enforcement justification is there to provide protection when they go on to commit further offences or to engage in further criminal conduct.
I would think the private investigators should be pretty much exempt from an offence where the requirement is not simply that they use fraud to obtain the information but that they do so for the purpose of going on to commit fraud or impersonation.