[aabecame]

Can B-4 be reprogramed by Dr. Soong?
B-4 • Once per game, may gain a regular skill if not playing .
Dr. Soong • Once each turn, may reprogram any androids present.
Now the Glossary says: This personnel may "reprogram" only those androids which have variable features chosen when it reported for duty.
At that time that was the only time they could be chosen.

[Armus]

Can B-4 be reprogramed by Dr. Soong?
B-4 • Once per game, may gain a regular skill if not playing .
Dr. Soong • Once each turn, may reprogram any androids present.
Now the Glossary says: This personnel may "reprogram" only those androids which have variable features chosen when it reported for duty.
At that time that was the only time they could be chosen.

Short answer is No, he can not, for the reason in the Glossary that you stated.

This got asked and answered in one of the Nemesis release threads, though at the moment I don't recall which one.

[jadziadax8]

This got me wondering if there are other androids that Soong could reprogram if his glossary entry were expanded to include all sorts of skill gain. The answer appears to be not really. All the other androids that have varying skills choose them when they report for duty. The only edge case I could see is it would make Not Programmed to Respond a bit more powerful. You could pick a skill, use it for a mission attempt, and then have Soong change it out for a new skill for a new attempt at a different mission.