No, they could not be. How can we (not just I) be certain of this? Here is how:
Rev 12:7
And there was war in heaven: Michael and his angels fought against the dragon; and the dragon fought and his angels,
Rev 12:8
And prevailed not; neither was their place found any more in heaven.
Rev 12:9
And the great dragon was cast out, that old serpent, called the Devil, and Satan, which deceiveth the whole world: he was cast out into the earth, and his angels were cast out with him.
Rev 12:10
And I heard a loud voice saying in heaven, Now is come salvation, and strength, and the kingdom of our God, and the power of his Christ: for the accuser of our brethren is cast down, which accused them before our God day and night.
Rev 12:11
And they overcame him by the blood of the Lamb, and by the word of their testimony; and they loved not their lives unto the death.
Rev 12:12
Therefore rejoice,
ye heavens, and ye that dwell in them. Woe to the inhabiters of the earth and of the sea! for the devil is come down unto you, having great wrath, because he knoweth that he hath but a short time.
Rev 12:13
And when the dragon saw that he was cast unto the earth, he persecuted the woman which brought forth the man
child.
Rev 12:14
And to the woman were given two wings of a great eagle, that she might fly into the wilderness, into her place, where she is nourished for a time, and times, and half a time, from the face of the serpent.
This war in heaven has not taken place yet. When it does take place, it will be the fulfillment of what the prophet Daniel prophesied here:
Dan 12:1
And at that time shall Michael stand up, the great prince which standeth for the children of thy people: and there shall be a time of trouble, such as never was since there was a nation
even to that same time: and at that time thy people shall be delivered, every one that shall be found written in the book.
In other words, this war in heaven will usher in the great tribulation which will last for
a time, and times, and half a time (Rev. 12:14) or for 3 1/2 years. If these angels were already bound in chains unto the day of judgment, then they would not be partakers in this yet-future heavenly war. Furthermore, we have portions of scripture like this one to consider:
Eph 6:12
For we wrestle not against flesh and blood, but against principalities, against powers, against the rulers of the darkness of this world, against spiritual wickedness in high
places.
Our fight, as Christians, is against spiritual wickedness in high places or in heavenly places. The Greek word
epouranios, which is here translated as
high, appears 19 other times in the New Testament. 16 of those times, it is translated as
heavenly. 2 of those times, it is translated as
celestial. 1 of those times, it is translated as
in heaven.
https://www.blueletterbible.org/lexicon/g2032/kjv/tr/0-1/
In other words, most fallen angels still have access to the heavenly realms (there are three heavens in scripture - 2 Cor. 12:2). Again, it is only a select group of angels who are presently being held in chains unto the day of judgment, and they are those who sinned by leaving their first estate, and/or their own habitation. Seeing how their first estate and/or their own habitation was originally heaven, where could they have possibly gone but to earth in their sin?