"I wasn't going to tell you everything! Just about the cyclopes armies mosseed on either shore and raging storm spirits."(Riordan 23)
Jason goes undercover to find information that his team needs. This information could change the future outcome. They don't know if there are enemies ahead for the straight path, or they can go around the island. The team does not know what path to take.
"Well, what do we do now?"(Riordan 38)
Jason sat down at a tables and a man started taking about all of the defenses they have and have powerful they are. He is saying that "These demi-gods will never get past our defenses!" This man tells Jason that the straight path is heavily defended.
Sail around the Peloponnese. As you suspect, this is the only route. On your way seek out the goddess victory
The man gave Jason the information he needed not even realizing he told him very important information and this would have the team take a path around the outside of the island avoiding the dangerous path ahead. It may take longer, but it is a lot safer.
Jason got the information about which path to take but was stopped by the goddess Hera and she tells them about the goddess of victory.
They are told that they need to help the goddess of victory. She is out of control and she needed help.
This would later turn the whole plot because Nike would help them beat the giants. If they never found Hera, they would have never gotten this help.