Cato the Elder was living in a time when many of his contemporaries were succumbing to the appeal of more hellenistic values. The most notable example of this is Scipio Africanus (the Elder); the honours and wealth which he'd earnt after his victory vs Carthage at Zama in 202BC were a strong incentive for other Romans to strive to do the same. The Scipio family was seen by Cato as a rival in their love of Greek culture, philhellenism. The influence Polybius had on the family after he was taken to Rome is an interesting topic, but I'm going off on a bit of a tangent.

In a nutshell, 'Greek values' were typically characterised by a love of luxury and excess. This was what Cato despised most of all; being a very conservative man, he believed that luxury and excess, imported from Greece to Rome via philhellenes such as Scipio, were a corrupting force in the Republic. The triumph is a strong example of a Roman tradition which became 'increasingly "hellenized"' throughout the period, and shows quite well the kind of perceived Greek values which Cato was opposed to. The triumph of Flamininus, as Livy tells us, lasted three days and showcased 'three thousand seven hundred and fourteen pounds of gold' (which may be hyperbole, but it can still be gathered that there was a lot of gold). Cato instead chose to stick with his Roman traditions, in that he aimed to be as limited as possible in his relationship to the material world. Furthermore, allowing novus homo (men who had gained a position of political influence and significance in Rome without having had any important heritage) to become more common would water down the aristocracy and consequently move power further from the hands of a few.

As well as this, I'm tempted to summarise his political views on the Greeks by saying that he was opposed to the diplomatic approach when it came to foreign policy. There's his classic 'Carthage must be destroyed' quote which most know about, which clearly shows he favoured a militaristic approach in order to exhibit Roman dominance. Earlier on in 184BC though, the year of his censorship, came the decision to act in response to the revolt of Sparta against the Achaean League (which had occurred 5 years previously). It's undeniable Cato had at least some influence on the Senate's decision, first because of the drastic policy change, and secondly because of the powers of the censor which (simply put) allowed him to pick and choose who sat in the Senate. Rome's intended approach to Greece in the second century BC seems to have been one of care, in that there appears to have been an effort to keep an eye on Greek public opinion throughout the course of Roman expansion in Greece. Cato, however, was untrusting and xenophobic, and therefore treated the Greeks like he treated the Carthaginians.

(According to Plutarch, Cato believed that Greek doctors were forming a conspiracy, by which they would integrate themselves within Roman society and slowly kill off everyone with their medicine. I don't know how true that is, but it certainly captures Cato's general attitude towards the Greeks).

Sources:

This is just off the top of my head, had an exam on it a week ago. In any case, some good books on the subject are:

Specifically relevant:

-Alan Wardman, Rome's Debt to Greece -Plutarch, Life of Cato the Elder -Polybius, The Histories -Mary Beard, The Roman Triumph -Livy, The History of Rome (XXXIV.52 details Flamininus' triumph)

General Coverage of the Period and Cato:

-Crawford, The Roman Republic -H.H. Scullard, History of the Roman World 753-146BC

TL;DR: Greek values (to Cato) = luxury, excess, (implicitly) democracy, conspiratorial doctors. Roman values = humility/honour and virtue, maintaining the aristocracy.

Edit 1: added Polybius to sources. He's a really good read and helpful in understanding the relationship Romans such as Scipio had with the Greek world.

Edit 2: added info on the triumph from Livy and Mary Beard, to exemplify the hellenisation of Roman traditions and Cato's objection to this.