I don’t think that was the reason. TrueCrypt was always available for use for free, so there was no lost licensing fees or anything. The anonymous developer(s) of TrueCrypt simply chose to stop developing it without explaining why (though more about that in a bit). TrueCrypt was forked by a couple of projects, and one that has continued development is VeraCrypt, which has all of the features of TrueCrypt and supports opening TrueCrypt volumes, including the “plausible deniability” of hidden volumes, allowing two different passwords to unlock two different storage containers. However, the full disk encryption remains a feature only of Windows - you can’t do that with a Mac. See https://www.veracrypt.fr/en/VeraCrypt%20Hidden%20Operating%20System.html
I continue to use VeraCrypt for a few things, though not for full disk encryption. However, if you want this feature for a travel computer and you can use a Windows PC, it is an available option if you feel that you are at risk of having your technology searched at the border.
As for the explanation of the stopped development of TrueCrypt, a couple of years ago Atavist Magazine did a series of articles detailing a man named Paul LeRoux, who was part of a money laundering drug cartel, and suggesting that he was the author of TrueCrypt. It was an interesting series and I believe that the timing of his arrest does coincide with the end of development announcement. The series is here: https://magazine.atavist.com/the-mastermind but I believe it was Part 3 of the series that had the most details about LeRoux and the suggestion that he was the developer behind TrueCrypt.