I've made an observation with 1.0, but I'm not sure if it's entirely true.

I think that the Old Man has a greater chance of spawning when you use 914, and I think this
for 2 reasons.

One, he spawned while I was using it,

Two, he spawned while Mirocaine was using it (as seen here: http://youtu.be/XOMAj7LtBZ8?t=12m34s)

Can anybody confirm or deny this?

It also happened to me.

106 wanted my ass every single video in that series. His spawn is also bugged, he randomly spawns underneath you at times (which is ok) - but this can happen while you're in SCP-860 aswell (as you'll see in my seventh video). WTF REGALIS, SCP-106 = OP I DEMAND A NERF TO HIM. GG NO RE

Riot, please nerf 106. His Q and Ult are incredibly powerful and need to be nerfed. Thanks for reading this Riot Games.

It has happened to me at least 6 times total, only once in 1.0 though, but that was the only time I've even used the machine in 1.0.

Scanned through the code and saw nothing relating 106's spawn chance with 914, maybe you're just hanging around in there too long *shrug* Or the game is sapient

That's weird. I'm gonna test it some more and see what happens.

EDIT:

Ok, after about 10 minutes of randomly using 914, using key cards, and gas masks, etc. The old man never spawned once. Maybe it is just a coincidence.

Pretty sure he has a spawn timer, maybe by coincidence it ran out while you were in there.

This used to happen to me quite a bit. Every time I go in to 914's room now the only thoughts on my mind are "hurry the hell up Idon'twanttodie".

SCP-914 requires you to stay there for a long period of time.
SCP-106 appears at random, what happened to you seems to be bad luck.