Plutarch's Lives says this about Marcus Cato:
He would likewise say ... and that in his whole life he most repented of
three things; one was, that he had trusted a secret to a woman;
another, that he went by water when he might have gone by land; the
third, that he had remained one whole day without doing any business
I hesitate to try and answer this because I am not really sure there is an answer. I like to read about Roman history and I have heard of multiple theories as to why he turned back. I think the most believable is stated in the 2013 LiveScience article Spartacus: History of Gladiator Revolt Leader by Owen Jarus:
“Many theories have been proposed, but the ...
According to both Livy (died circa. AD 17) and Dionysius of Halicarnassus (died after 7 BC), Mettius Fufetius's intention was to observe how the battle went and then join the winning side. In doing so, he was prepared to betray both sides for he had made promises to both the Romans and the Etruscans.
Livy attributes this prevarication to a lack of courage. ...