Can kolasis in classical Greek mean ‘pruning’ rather than ‘punishment’?

Unlikely. This is based on the similarity between kolouo “to prune” and kolazo “to punish”, which may or may not indicate a shared etymology earlier in the Greek language. It is evidenced only by one text – a literal reading of an instance by the botanist Theophrastus of the ‘punishment’ or ‘pruning’ ‘docking’ of an almond tree. But critically the text only remarks that “some call it” punishment, this is not the same as punishment being a normal use by some farmers, or that the meaning of punishment by some farmers, presumably a regional oddity, changes the meaning of the word.

Into the almond tree they drive an iron peg, and, having thus made a hole, insert in its place a peg of oak-wood and bury it in the earth, and some call this ‘punishing’ the tree, since its luxuriance is thus chastened (Theophrastus, Botany Book III) 

In any case, the context where used of humans in all extant Greek texts, classical or Jewish (notably the Septuagint and New Testament) shows that the context with humans is punishment. In most cases fatal and permanent.

source:

Midwestern Journal of Theology 10.1 (2011): 124-29 Cutting-Edge Obsolescence: Rob Bell’s Reliance on a Long-Discredited Universalist Rendering of Matthew 25:46 in Love Wins RONALD V. HUGGINS Associate Professor of NT and Greek Midwestern Baptist Theological Seminary Kansas City, MO 64118 rhuggins@mbts.edu https://biblicalstudies.org.uk/pdf/midwestern-journal-theology/10-1_124.pdf  “…. By the time the 9th edition of Liddell & Scott appeared in 1940, however, the situation had changed. The words “Properly, to curtail, dock, prune” were dropped from the definition of kolazo, to be replaced by “a drastic method of checking the growth of the almond-tree.” As for kolasis, the definition “a pruning or checking the growth of trees,” was shortened to read instead “checking the growth of trees,” with the additional clarification: “esp. almond-trees.” In addition to all this the entire reference to the distinction between kolazo and timoreomai (i.e., timōria and kolasis), along with its supportive appeal to Aristotle, were removed. This change of opinion reflected in Liddell & Scott signaled an apparent loss of confidence concerning an assumed historical connection between kolazo/kolasis and kolos (“docked”)/kolouo (“to dock,” “prune”). Liddell & Scott had originally derived their affirmation of this assumption from their German source, Franz Passow’s Handwӧrterbuch der griechischen Sprache. In the earliest edition of Liddell & Scott I have access to (1848), they are very confident about the connection, saying in reference to kolazo that it is “No doubt akin to kolou/w [kolouo]” and as a result “strictly to curtail, dock, prune.” In subsequent editions the “No doubt” was downgraded to a “Prob. [Probably],” and then, ultimately, dropped altogether. I cannot help but suspect that part of the difficulty lay in the fact that the only examples offered where there was any sort of clear horticultural connection with kolazo/kolasis derived from a single author, namely Theophrastus of Eresos (3rd/4th cent. BC), and in particular to a passage in a work where he used kolazo in a sense in which the concept of punishment appears already to be there. Consider Arthur Hort’s Loeb Classical Library translation of the crucial passage where kolazo is used: “Into the almond tree they drive an iron peg, and, having thus made a hole, insert in its place a peg of oak-wood and bury it in the earth, and some call this ‘punishing’ the tree, since its luxuriance is thus chastened (o^ kai\ kalou`si/ tine$ kola/zein w($ u(bri/zon to\ de/ndron).” 6 More directly, that final phrase would read something like: “which some call ‘to punish,’ as the tree was running wild.” It is primarily this passage that provided the current edition of Liddell with its revised definition “a drastic method of checking the growth of the almond-tree.” And please note that Theophrastus’s language has more to do with stunting growth than, to recall Rob Bell’s words, “the pruning and trimming of the branches of a plant so it can flourish.”

8th edition
https://logeion.uchicago.edu/%CE%BA%CF%8C%CE%BB%CE%B1%CF%83%CE%B9%CF%82

κόλ-α^σις , εως, ἡ,

https://logeion.uchicago.edu/%CE%BA%CE%BF%CE%BB%CE%AC%CE%B6%CF%89

LSJBailly 2020PapeGrieks NederlandsMiddle LiddellExamples from the corpusLSJBailly 2020PapeGrieks NederlandsMiddle LiddellExamples from the corpus