"My sheep hear My voice, and I know them, and they follow Me. And I give them eternal life, and they shall never perish; neither shall anyone snatch them out of My hand. My Father, who has given them to Me, is greater than all; and no one is able to snatch them out of My Father's hand."
OSAS Christians continue to say this verse supports OSAS even though it does not. They skip over the words "and they follow me". As long as you follow Christ, you continue to be His sheep. Stop following Christ and you remove yourself from being His sheep.
OSAS would be supported (established) if that verse said: My sheep hear My voice, and I know them, and they cannot (or will not) stop following Me. But it does not say "they cannot (or will not) stop following Me". If OSAS was correct, it would say that. The fact is this verse implies that OSAS is not correct.
However, OSAS Christians have been told that this verse means OSAS for so long and so often, that we will continue to see it being used to support OSAS.
More often than not what you have is folks merely repeating what they have been taught. You are correct that this verse does not support OSAS, as the context is not eternal salvation. However just because folks use some bad texts to try and prove their point, doesn't make their point invalid
If folks would just stick with Acts 16:30-31 and Ephesians 2:8-9 they simply wouldn't need to go anywhere else in Scripture as those two texts alone show without a doubt that once a person is saved they are always saved for eternal purposes.