The Bhavishya Purana is one of those scriptures which is not available in its authentic form. There isn't a single manuscript available now.
It has been altered and modified by so many people to suit their needs that now, it's nothing more than a couple of Sanskrit slokas. Stephen Knapp describes it best:
However, I should also point out that this prophecy of Jesus in the Bhavishya Purana is found in no other Puranas, which often corroborate each other. This is why a study of the 18 major Puranas will reveal an assortment of prophecies that are often repeated one in another. So to find this story of Isha Mashiha in no other Purana sends a red flag of warning. Furthermore, not everyone gives the Bhavishya Purana pure confidence. It is known that as many as 200 pages from this text had become lost or misplaced, and various interpolations are likely to have occurred in this text while India was under the British administration. So, we should be somewhat cautious about accepting this on face value.
However, there are presently four known editions of the Bhavishya Purana, each having different predictions from the other, but suspiciously having one consistent prediction - that of Jesus or Isha Masiha. One edition contains five chapters, one contains four, another contains three and yet another contains only two. Additionally, the contents in all four editions differ in various degrees - some having extra verses and some having less. Due to these circumstances, it is difficult to ascertain which of the four is the original text of the Bhavishya Purana, if indeed an original text still exists, but suspiciously, as mentioned, all four editions do mention Jesus.
The Venkateswar Steam Press edition of the Bhavishya Purana printed in Bombay in 1829 (and reprinted by Nag Publishers in 2003) is probably the most complete version available, containing all the main features of the four manuscripts. Since none of the four editions of the Bhavishya Purana predate British Rule in India, this further suggests a discrepancy. The fact is that the British tried to monopolize the publishing of all Sanskrit literature during the British Raj. They bought or confiscated any Sanskrit literature they could locate. And that is why you practically cannot find any Vedic literature that is published before 200 years ago. It is further known that they liked to publish their own translations, as if India could not produce its own Sanskrit scholars to translate the Sanskrit themselves. Plus, they would also try to interpolate various verses here and there to have the reader draw a different conclusion of the personality or traits of the characters described in the texts. Most were quite noble, but by slipping in verses that said certain persons had less than admirable qualities or degraded habits, or that questionable practices were used, it would change the reader’s disposition and attitude toward such personalities or the Vedic culture itself, even if they were Indian born followers of it.
Therefore, the consistent prophecy of Jesus in all four editions of the Bhavishya Purana, in spite of the differences in the editions found, seems to indicate an interpolation regarding the so-called meeting of Maharaja Shalivahana and Jesus. This is found in the 19th chapter of the Pratisarga-parva. However, as B. V. Giri Swami relates, in examining this section, certain flaws can be found which betray its dubious origins.
So, basically it looks like a cooked up story with motives unknown. The complete article is "Jesus Predicted in the Vedic Literature?".