Comer vows hearing will proceed "with or without" Hunter Biden.
Biden previously rejected invitation, citing scheduling conflict and branding hearing a "carnival sideshow.
Comer asserts importance of public scrutiny of Biden's involvement in family business dealings.
Committee asks Biden to reconsider refusal for public hearing in the interest of transparency.
Hunter Biden's legal team has repeatedly sought public hearing.
Biden flouted subpoena for private deposition in December, demanding public hearing.
Comer emphasizes Biden's opportunity to provide perspective alongside business associates.