The sections you quoted don't support this statement. The quoted statements highlight contractual clauses which include "excessive" foul language which one instance of calling someone a dickhead does not approach. The only point a single instance of swearing could be grounds for dismissal were against a customer, which is specifically highlighted in the contract.

Were the contract to include a clause of "you will not swear at other employees," then that would have been sufficient. Now, whether that falls foul of the Equality Act (due to discriminatory treatment) is a different question. You can't extrapolate any result of that from this case, however.