Your person probably wants to say "Each of the Algerians is..." instead. But, contrary to what @deadrat says, there is usually no problem with using "all (of the)" to refer to individual members of a group, e.g.,
- All (of the) employees received a raise proportional to their seniority.
- All (of the) players touched the ball at least once in the lead-up to the goal.
- All (of the) riders were asked to provide a urine sample.
In fact, note the following sentence, which has the intended meaning that the predicate "be point guards" holds of each of of the individuals that make up the group, but not of the group itself. This is the meaning that the OP's colleague intended for "be one of the individuals that...".
- All (of the) players in the team are point guards.
Compare to the following, which is odd in the same way as the OP's sentence. It means that, collectively, the players constitute one single point guard. This somehow conjures up a Power Rangers scenario where the players assemble to become parts of a larger entity.
- All (of the) players in the team are one point guard.
In short, if you want to use the "All (of the) [noun] are [predicate]" construction, where [predicate] distributes over members of the group denoted by [noun], then [predicate] has to be a bare plural (or an adjective, cf. "all (of the) players are married") rather than a noun phrase headed by "one (of the)".