I'm not sure that is correct because the blades aren't any different than mechanical broadheads that rear deploy. I just checked the regs and the only two discussion about BH's are from page 85:
Section a. Mechanical broadheads are legal to use for all archery hunting
Section f. It is unlawful to hunt big game animals with any arrow or bolt that does not have a sharp broadhead, and the broadhead blade or blades are less than seven-eighths inch wide.
Kinda looks that way, as the only specific restriction is mentioned is under the WAC regarding crossbows.
WAC 220-414-070
Archery requirements.(1) The following provisions apply to all archery hunting seasons:
(a) It is unlawful for any person to carry or have in his possession any firearm while archery hunting in the field during an archery season specified for that area, except for modern handguns carried for personal protection. Modern handguns cannot be used to hunt big game or dispatch wounded big game during an archery big game hunting season.
(b) It is unlawful to have any electrical equipment or electric device(s), except for illuminated nocks, attached to the bow or arrow while hunting.
(c) It is unlawful to discharge a bow from a vehicle or from, across, or along the maintained portion of a public highway.
(d) It is unlawful to use any device secured to or supported by the bow for the purpose of maintaining the bow at full draw or in a firing position.
(e) It is unlawful to hunt big game animals with any arrow or bolt that does not have a sharp broadhead, or with a broadhead blade or blades that are less than seven-eighths of an inch wide.(f) It is unlawful to hunt wildlife with any bow equipped with a scope. A verifier peep sight that magnifies the sights is not considered a scope and is lawful.
(2) The following provisions apply to long bow, recurve bow and compound bow archery equipment:
(a) It is unlawful for any person to hunt big game animals with a bow that does not produce a minimum of 40 pounds of pull measured at 28 inches or at full draw.
(b) It is unlawful to hunt big game animals with any arrow measuring less than 20 inches in length.
(3) A violation of this section is punishable under RCW 77.15.400, 77.15.410, or 77.15.430, depending on the species hunted.
WAC 220-414-100
Crossbow requirements.(1) The following provisions apply to hunting with a crossbow:
(a) It is unlawful to hunt big game with a crossbow outside of a modern firearm season.
(b) It is unlawful to hunt big game animals with a crossbow with a draw weight less than 125 pounds and a trigger safety that does not work properly.
(c) It is unlawful to hunt big game animals with any arrow or bolt weighing less than 350 grains.
(d) It is unlawful to hunt big game animals with any arrow or bolt that does not have a sharp broadhead and the broadhead blade or blades are less than seven-eighths inch wide.
(e) It is unlawful to hunt big game animals with a broadhead blade unless the broadhead is unbarbed.(f) It is unlawful to discharge a crossbow from a vehicle or from, across, or along the maintained portion of a public highway.
(g) It is unlawful to hunt wildlife with a crossbow during an archery season.
(2) A violation of this section is punishable under RCW 77.15.400, 77.15.410, or 77.15.430, depending on the species hunted.