For what it is worth, the listing says they are made from A536 iron which looks to be different than simple gray iron used for things like engine blocks. One site defines it as ductile iron and describes it as this:
Ductile Iron
Standard Specifications Characteristics Applications
• ASTM A395 & ASME SA395: ferritic ductile iron pressure-retaining castings for
use at elevated temperatures
• ASTM A439: austenitic ductile iron castings
• ASTM A476 & ASME SA476: ductile iron castings for paper mill dryer rolls
• ASTM
A536 & SAE J434: ductile iron castings
• ASTM A571 & ASME SA571: austenitic ductile iron castings for
pressure-containing parts suitable for low-temperature service
• ASTM A874: ferritic ductile iron castings suitable for low-temperature service
• ASTM A897: austempered ductile iron castings
Several grades for both
strength & ductility; high
strength, ductility & wear
resistance; contact fatigue
resistance; ability to
withstand thermal cycling;
and production of fracture critical
components.
Steering knuckles; plow
shares; gears; automotive &
truck suspension components;
brake components; valves;
pumps; linkages; hydraulic
components; and wind
turbine housings.
The whole document can be found here:
http://www.afsinc.org/files/images/iron%20alloys.pdf
My point is that this lists this kind of iron as being used for things such as steering knuckles and brake components so it must be pretty tough and not entirely brittle like gray iron can be. The description specifically says it is used for fracture critical applications. Not making an argument for or against the tow hooks just offering this information for what it may be worth to add to the discussion.