Males don't get pregnant. What happens is they have this pouch on their stomach, and the females lay the eggs in the pouch. Once the eggs hatch, they emerge. It LOOKS like the seahorse gets pregnant, as it gets very fat and then apparently gives birth, but it's not pregnancy. There is no connection made from the male's body to the eggs, and the male does not produce the eggs.
A good comparison would be the pipefish. Pipefish females stick the eggs all over the male's tail. The male most definitely isn't pregnant, it just carries the eggs.
And the article is incorrect, yes. Seahorses can swim reasonably well (for seahorses) in flow, and they can be kept with other fish.
Basic requirements for a seahorse tankmate:
Should be smallish and not overly hyperactive/flashy, though some larger seahorses will peck anything small that gets annoying- usually the thing learns to leave them alone.
Shouldn't be predatory or nippy, of course
Should be okay with the temperatures
Preferably shouldn't get all up in their space
For example, gobies and jawfish should be fine. Depending on the horse, green chromis could work- larger species of seahorses shouldn't mind. Yellowtail blue damsels can work, if it's a small damsel and a larger horse- yellowtails can be a bit puffy, but large seahorses will peck them and make them go away if they get irritating. I have seen this for myself, with a rather bossy little 1 1/2" damsel and a 4 1/2" tall seahorse. Damsel was doing his usual tail-in-yo-FACE thing, seahorse got irked and pecked him a couple of times. Damsel left him alone after a couple of repeats. Best not to keep any kind of damsel with a small seahorse, though.
That's just off the top of my head.