Understood it that way, this seems pretty logical.
"These are the rules here. You can accept them, and stay. If you don't, fine, there's no problem, we won't hold any hostility towards you for this, but we don't want you in our covenant."
Controlling? Nope.
Paranoid? Certainly
Security, and Fear. Just as IRL
If a mage knows he has nothing to fear (he did nothing against the code) and is paranoid about diedne, diabolists, the order of suleiman, faeries infiltrators and such, he might, IMO, readily agree to this: You know you're probably safe there, not like that covenant over there, which, if you trust the villagers, is infested with a least one evil bay-eating magus. Despite the gift, there isn't smoke without fire, is it?
Another exemple? Dimir Taar, with his bloody magic, might have easily be mistaken for a diabolist or a druid. With such a investigation, his covenant mates knew his matter, and thereafter he, was clear.
He didn't enjoy it at all, but, paranoia-wise, perfectly understood the necessity to submit himself to the investigation in order for it to work, and, thereafter, his covenant mates knew they could trust him on this.
We're talking of a world with unknown ennemies and dangers, not the local grocery store.
RL doesn't have an Order of Odin or supernatural hazards
Real-Life wise? What security agency would give access to secure data to someone they hadn't screened first? What firm would ask for a firm to build important parts of, say, an Airbus without checking the firm's references before?
Hum. Covenant Charter here?
There are covenants when older magi have every right, junior magi none, they just wait, hoping to become themselves senior magi one day.