There are a lot of misconceptions regarding what Traditional Chinese characters actually means. The most accurate way to describe this set of characters is that it contains all characters that were not first described in the Chinese Character Simplification Scheme of the PRC or Joyo Kanji of Japan.
Importantly, note that Taiwan and Hong Kong both have their own prescribed standards of Chinese character usage, and although both are commonly known as Traditional Chinese, they do not entirely overlap. The same extends to the Korean standard, which is largely based off the Kangxi dictionary with some tidying-up applied afterwards. Hanja thus are very often more conservative than their counterparts in Taiwan and Hong Kong, e.g.
All Hanja must be written and displayed according to the Korean standard, and not any other standard, so no, you cannot use simplified Chinese characters for Hanja.