If the charges are true, which I personally doubt, it would represent a drastic change in the tactics the group has utilized to date. Still with so much confusion caused by premature and mistaken reporting one could do little better than reading al-Qadhi's piece.
One thing he does not make explicit is in this paragraph:
"This incident comes just a day after 24 medics who had been kidnapped in the northern province of Amran by armed tribesmen were released. The kidnappers wanted to pressure the government to release some of their relatives."
The 24 medics, with the exceptions of the Saudis, were not from countries that would push the government to act quickly. The nine foreigners - including Germans, were. I'm not saying the same group is behind both - but if I were a tribesmen looking to kidnap someone to force the government's hand, I would be looking for someone with a western passport.
Hasan Naif weighs in at the end of the piece:
"It is difficult to believe the denial of al Houthis or the accusations of the government. What is dangerous is that kidnapping has become a tool of political manoeuvres where the two sides are exchanging accusations and the blame. This shows the state’s predicament."
I part company with this very astute observer of Yemen here. This case is more about the government and the Huthis both trying to put their own political spin on an case that isn't related to the conflict between the two - its only relation is the accusations both sides are flinging at each other.
Also, kidnappings, like it or not, are an accepted tool of politics in Yemen. This didn't just happen it has been on-going for quite some time, pre-dating the war in the north.