Eldritch Knight fighters have the ability to bond with a weapon, a ritual which gives the following property (PHB, p. 75):

Once you have bonded a weapon to yourself, you can't be disarmed of that weapon unless you are incapacitated.

There are two instances of disarming (that I know of) in D&D. One of them is the Disarming Attack from the Battle Master fighter archetype, and the other is the optional Disarm action option contained in the Dungeon Master's Guide.

The Telekinesis spell allows the caster to potentially steal a held item from another creature, including a weapon:

If the object is worn or carried by a creature, you must make an ability check with your spellcasting ability contested by that creature's Strength check. If you succeed, you pull the object away from that creature and can move it up to 30 feet in any direction but not beyond the range of this spell.

Does an Eldritch Knight's Weapon Bond protect him from losing his weapon to a Telekinesis spell?

The Eldritch Knight's Weapon Bond protects them from Telekinesis-used-as-disarmament

In 5th edition D&D, there's not much difference between Disarming (upper-case 'D') an opponent and disarming (lower-case 'd') an opponent, except that the former represents a specific attack action/feature, and the latter is just a vocabulary term. If the feature for Eldritch Knights specifies that the knight cannot be disarmed of their weapon, then no effect, magical or non-magical, can cause a knight to be disarmed, irrespective of whether the effect in question explicitly says it is a disarmament effect, unless either the knight is incapacitated, or the effect is explicitly qualified as bypassing an Eldritch Knight's disarmament immunity.

Yes, the bond prevents disarming regardless of the cause.

You've cited a few game rules that allow disarming, but the term isn't explicitly defined otherwise. So we rely on the meaning of the word "disarm," which is "to deprive of weapon(s)." The Eldritch Knight's weapon bond makes no exception to how they might be disarmed: they simply can't be disarmed. Neither telekinesis nor sleight of hand nor any other means short of incapacitation can disarm them of that weapon.

Yes, Eldritch Knight's Weapon Bond is more specific than Telekinesis' object movement, but it only applies to his bonded weapons.

Because there's little RAW detail on the mechanics of disarmament, I'm going to refer to the plain English definition of "disarm":

dis·arm /disˈärm/

verb

1. Take a weapon or weapons away from (a person, force, or country).

The DMG variant rule on disarming reflects this plain English understanding and the Eldritch Knight's class feature Weapon Bond specifically prevents this scenario happening.

Whether or not the weapon has to be in the Knight's hand is up for debate, as the DMG describes Disarming as:

A creature can use a weapon attack to knock a weapon or another item from a target's grasp. The attacker makes an attack roll contested by the target's Strength (Athletics) check or Dexterity (Acrobatics) check. If the attacker wins the contest, the attack causes no damage or other ill effect, but the defender drops the item.

Clearly, Wizards' view disarmament as removing weapons when they are in the opponent's grasp.

So, ultimately, it's up to you whether Telekinesis can disarm an Eldritch Knight of his weapon when is on his person, but not in his hand. I would personally rule that you could, since the Knight can summon the weapon back to his hand as a bonus action, creating interesting counterplay for a feature rarely used.