It’s one thing to buy a dragon with lore, say “I like this lore idea but the gender isn’t gendering”, and change it. That’s your dragon, and it’s your character. Even then, it’s considered best practice to not include other people in your lore without their permission; it’s one thing to say “this dragon came from a bad background” and another thing to say “this dragon came from a bad background [describes previous owner’s lair/lore in a way that implies the previous owner specifically as being bad]”.

It’s another entirely to change the gender on a traveling dragon (rude, since the polite thing to do is assume that dragon isn’t yours permanently), then when the OG owner is unhappy about it get pissy and keep it out of spite because you don’t want the lore altered. All those things combined smack of something Not Cool.