Flaming sphere sustain instructions a bit unique as Hypersmerf pointed out. Pg 278 on sustaining is a general rule which can be trumped by the specific, i.e. sustain as minor until the end of the encounter, as a standard action you can make another attack with the sphere. Applying this literally, the wizard would conjure the sphere attack with it, next turn he can sustain it as a minor action, and make another attack as standard action, that turn or later and dealing damage to anyone starting there turn next to it in the mean time. But after that another attack it would be a rolling hot foot, that could be moved as a move action to deal damage to those starting next to it.
I am not saying that I think that this is what they intended, but applied literial I think this is the result or close to it.
Yes, this is precisely what one can do with flaming sphere. As long as one sustains it each round first, they can (but do not have to) attack with it with a standard action and can (but do not have to) move it to damage foes on the start of the foe's next turn. Moving it without sustaining it on a latter turn (after the first) is worthless since it will expire at the end of the Wizard's turn if not sustained.
But, your statement here is not what Hyp was questioning.
One cannot do the standard action without sustaining first in the same turn because the standard action is part of the sustaining description:
Page 59
"The "Sustain" entry tells you if a power has an effect that occurs when you take the action to sustain it.
If one does not take the action to sustain it, one does not get the sustain effect.