This is what EWR is all about -- you never know what you are going to get on any given day - like when they stopped accepting print at home BP out of the blue...

FWIW - I've entered the Polaris lounge on an LX ticket leaving from B and had no issues - but clearly EWR/TSA management does what they want when they want. For example, let's say your flight came into C in the above example -- and you were connecting to B -- you would not have an issue getting in to the PL -- so it's all just a YMMV with airport operations...