They are extremely afraid, freaked out, or paranoid that people are going to use Parler to somehow overthrow the government. But, they were not afraid that people were going to use unverified mail in ballots and ballot stuffing to overthrow the government. In reality we all know their fear is a ruse and this is a power grab.
My understanding is that repeatedly, the courts have shown that allegations about widespread voter fraud are unfounded. Do you have evidence to the contrary?