How do you think the 38th would react to Vashtorr popping in to say hi.

Knowing Sloan's record he has fought Vashtorr and lost after he built a better robot or gun than Vashtorr and Vashtorr reacted poorly.

The Harvest of Steel may be a significant enough creation to have attracted Vashtorr.

Solon would probably be polite to him but weary about what Vashtorr might want from him.

Gala might dismiss him in her cold mechanical way as she might see him as a false machine god.

Some ponies might be like "There was another god we could have chosen?" and then need it explained to then that Vashtorr was, if anything, a minor chaos god and really only appealed to "massive chaos-tech nerds"

welp, vashtor is a puny 5th god of chaos, I really bet that sol can defeat it

Vashtorr might start fangirling over Solon, the best engineering chaos space marine, whom he has always looked up to.