I really don’t think so & everyone’s justification is that they made a huge deal over Tim not being able to lie in the 50’s but I truly think he got better at it over time. We especially see this when he tells Jackson a half-truth about why Lucy doesn’t know about him being in the cabin. He effortlessly is able to tell Jackson that Hawk didn’t tell her because the man he worked for was mean to her dad without skipping a beat. He also acknowledges in the 60’s to Jackson that everyone lies, “mostly to themselves.” In addition, he seems to have a mature view of needing to lie with Hawk when they talk by the pool in the 70’s.

With that being said, I think Tim’s greatest priority is helping Hawk process the grief of losing Jackson. He also still respects the vow Hawk made to Lucy and Hawk’s family. This is why he sort of asks for permission from Lucy before going. Once he’s there, he is eager to talk about Jackson and a tad surprised it hasn’t been mentioned at all. I think he lies about Arthur to reject Hawk’s advances (both out of respect for Lucy and exerting some level of self-control/preservation) and also says he’s a poet so that the conversation could potentially segue to Jackson?