Denial due to a lack of evidence is unscientific, scientific is hypothesizing and seeking evidence.
No it's not. It is one of the most fundamental aspects of the scientific method. It does not preclude forming hypotheses and seeking evidence. You assume the 2 are mutually exclusive, but they're not.
Actually denial is precluding, it is a conclusion; and it is a conclusion that goes beyond unscientific to illogical since it tries to claim a negative due to a lack of evidence. Proper denial requires evidence to the contrary not ignorance. Denial is something different than "there is currently no evidence to support/demonstrate/etc".
"Argument from ignorance (from Latin: argumentum ad ignorantiam), also known as appeal to ignorance (in which ignorance represents "a lack of contrary evidence"), is a fallacy in informal logic. It asserts that a proposition is true because it has not yet been proved false (or vice versa). This represents a type of false dichotomy in that it excludes a third option, which is that: there may have been an insufficient investigation, and therefore there is insufficient information to prove the proposition be either true or false."