Legality of te-gatame
As one might infer from their presence in the video and current syllabus, the position of the Kodokan is that these bent-arm hammerlock versions of te-gatame are legal.1 2 3
The incongruence between te-gatame appearing on the IJF's list of legal techniques and the (occasional) penalisation of it in actual competition seems to stem from what the Kodokan consider a misunderstanding of the rules on kansetsu-waza prohibition:
Also, Tori who was trying to apply Ude-hishigi-te-gatame was given penalty as it was considered as an attack to Uke’s shoulder, with the current tendency of overreacting to hazardous actions. These seem to be caused by lack of knowledge rather than insufficient referee skills.
Note however that the IJF Referee Commission appear to be aligned with the Kodokan on this matter, having on several occasions demonstrated what appear to be Hammerlock style te-gatame as examples of a legal technique in ne-waza (forcing uke to turn over):
And such techniques have been awarded ippon in 4/5 occasions I can locate of it being used in high-level competition:
Ambiguous translations: scope of kansetsu-waza armlocks
The intention of the rule prohibiting non-elbow joint-locks seems to have been to include both armbar style locks and bent-arm locks, since both involve manipulation of the elbow joint to achieve their effect, regardless of the point of pain/hyper-mobility exercised on uke itself.
This is evident in Kodokan descriptions of the technique,1 2 3 where it is considered a lock applied "to" the elbow joint:
Ude-hishigi-te-gatame | Hand armlock
... It is also possible to grasp his wrist with one or both hands and apply a lock to his elbow by twisting his arm behind his back.
The common idea that "kansetsu-waza applied to the elbow" only includes "joint-locks which cause pain to the elbow" seems in light of this to be a misinterpretation.4
|"kansetsu-waza applied to the elbow"
||armbars and bent-arm locks
||only armlocks which cause pain to the elbow
The Kodokan makes this explicit in its clarified rules:
||Even if the elbow is attacked with "Ude garami" or "Ude hishigi waki gatame", the shoulder joint may be affected. If the shoulder is clearly attacked and the opponent loses the ability to play the match, the injured player will be the "foul-loser".
Note on translation:
te-gatame... Alternatively use one or both hands to grip your opponent's wrist and twist it around behind him to control his elbow joint.
- Kodokan New Japanese-English Dictionary of Judo
Kodokan Judo: The Essential Guide to Judo by Its Founder Jigoro Kano, Jigoro Kano (1997)
Kodokan Katame-Waza: Various Techniques and their Names (1994)
This is perhaps understandable given the inconsistent way in which the term 'joint-lock' is used in different martial arts and languages, sometimes referring to the action of 'locking' a position, and sometimes the point of pain inflicted in the locked position.
In addition to the general issues in translating technical and anatomical terminology from Japanese to English, I suspect the confusion is in part also due to the ambiguity of terminology for individual joint-lock names, referring variously to:
• the point of articulation/pain in uke when applied (Achilles-lock, wristlock, biceps slicer, omoplata)
• the articulation/movement of tori when applying (ude-garami, double wristlock)
• the articulation/movement of uke when applied (armbar, chicken-wing)
• or a combination of the above (ude-hishigi-hiza-gatame, knee-bar, toe-hold)