The other held a very vocal grudge against me for not doing my solo certificate with him - we'd only met once and when he found out I didn't do it with him he began to give me a lecture on how he doesn't take on half-baked divers. Which is when I cut it short.
Sadly, that is all too common, especially in the Tech instruction side where ego seems to be a bigger issue, it doesn't help here in UAE where there are limited options and few students so folks can get quite belligerent if they see "their" potential students going elsewhere. Sadly, it seems to be a dive culture thing here to bad mouth the "opposition", I refuse to play that game but I am also lucky that I don't do this as my primary income and can afford to be picky about who I play with.
Personally, I have found that most potential team mates and the good instructors really don't care how you got the skills and got squared away, just that you are. I actually try to encourage my students to do courses with other (reputable) instructors, there is a danger in doing all your training with one person, in that, best case scenario, you end up as a mediocre photocopy of them, bad habits and all.