By 462, imperial authority had mostly collapsed in most of Gaul since the death of Majorian and the former provinces were mostly controlled by local warlords or nobles, either Roman (such as Aegidius in Northern Gaul) or Barbarians (such as Euric). It wouldn't be accurate to consider Agrippinus as a "local military ruler" however.

What does Hydatius, a Spanish bishop with an axe to grind against Goths and Ricimer while praising Majorian's former lieutnants, had to say about it?

Agrippinus Gallus et comes et civis, Aegidio comiti viro insigni inimicus, ut Gothorum mereretur auxilia, Narbonam tradidit Theudorico.

Agrippinus Gallic count and citizen, an enemy of the illustrious count Aegidius, surrendered Narbonne treacheously to Theuderic to gain the support of the Goths.

Agripinus was made military commander for the whole of Gaul during Avitus' reign, but as Majorian ousted him he was sent to be tried in Rome only while Aegidius took his function.

Goths were settled in Aquitaine since 418, effectively forming an autonomous state in southern Gaul with their own palace and court. The death of Valentinian III and the political crisis in Rome mostly favoured them as they intervened in Gaul and Spain, demonstratively in the emperor's name but effectively consolidating their own authority.

An alliance was made between Avitus, then magister militum of Gaul, and Goths allowing the former to be proclaimed emperor, hopefully favourable to Goths in order to legitimize their increased authority. Ricimer and Majorian coup quickly put an end to this, and the new emperor even forced Goths out of Spain (and possibly out of the region of Narbo, although Goths were able to prevent Majorian to land in Narbonensis after his unfortunate campaign against Vandals);Ricimer having executed Majorian and Aegidius in open revolt, Agripinus was sent back to Gaul having recovered his former functions and gave Narbo to Goths as a gesture of good will in making an alliance between them and Ricimer : having the former commander for Gaul, the second of Avitus, doing so in a name of a new pact was certainly coherent enough and Ricimer was able to broke a deal with Theudeuric and Euric, the Gothic kings focusing their attacks on Aegidius.

Now, while this is not a case of a local ruler giving away a city. Euric certainly managed to gain the support of local Roman warlords and nobles during his reign : Victorinus was a noble from Auvergne and Vicentius from Tarraconensis. Burgundians managed to gain the support of a member of the Syagrii family, etc. With the collapse of Roman authority in western provinces, the most stable elements and courts were often Barbarians and biding themselves to what amounted to regional states was the best way to ensure political and social survival.

Does that means the whole gesture was appreciated in southern Gaul, let alone how it was in the northern part held by Aegidius and his Frankish allies? While it's probable that many local nobles had the same anti-Barbarian and anti-Arian perspective than Hydatius or Aegidius, there's no evidence it was a widely shared opinion : the whole thing simply doesn't seem to have been that shocking of an event.

Sidonius Appolinaris, senator of Auvergne, arguably paints Theuderic in the most favourable way in his second letter, as a "prince worth being known", a king busy with administrative and judicial duties, full of gravitas and moderation. In a word, a Roman general and a prince among Barbarians. It's true that our senator there was the son-of-law of Avitus and didn't embraced yet an anti-barbarian fashion that was both a way to show his displeasure with the aggressive expansionism of Euric and to gain some job security at the late imperial court.

Eventually, while anecdotal, that Leontius, one of the main jurisconsult and advisor of kings Euric and Alaric II, making a large part of the variation on Roman law that were the codes of Euric and of Alaric, was native from Narbo illustrate well the uncanny capacity of Roman aristocracy to adapt itself and be an active part of the Barbarian states.

- Late Roman Warlords; Penny McGeorge; 2002

- Chronicle of Hydatius