As long as the 10ks are not a weekly occurance, they should fit into an IM plan just fine. You need to work on running strength and speed in addition to the long stuff...
I'll go looking for more. I had everything bookmarked before my pc crashed a while back, and havent dug everything back up yet.

Joe Friel's Ironman plans have 6 races shorter than IMs built in- most Oly distance Dus.

This "marathon + cross training " plan has some fast paced stuff every week.
http://www.runnersworld.com/article/0,7120,ssssss6-238-244--8257-6-1X2X3X4X5X6-7,00.html

I would just say "if my coach says it's okay I'll be there - otherwise, no"

It's your plan, your body, your IM - no need to justify.

what do they expect of you? to win/place at each of these events? it is very difficult to rock the short and long course at them same time. if they just want you to show up and you treat some of them as "C" or "D" races then maybe but can't see how you can be expected to do well in all these different length events. as noted above check w/ friel's training bible think you can only expect one or two peaks a season.

Training for triathlon is very different than training for pure cycling, or any other single sport, for that matter.

When you train a single sport, it's much easier to 'race yourself into shape,' which is at some level what pure cyclists do. You can even do this running or swimming to an extent.

Pure cyclists are not training for 112-mile time trials, although they may still do long rides of 3 hours every week.

I would do more open running races if they weren't always on a Sunday when it's more important for me to ride long than it is to run a 5K-10K. Moving around your usual schedule can wreak havoc on your recovery, and most of us working stiffs can't fit in 3+ hour rides on weekdays, so that's the real reason a lot of us triathletes don't race so much, IMO.

Especially during the last 12 weeks of an Ironman build, your #1 priority is to keep at the long rides and long runs. If you are able to move those key workouts around in such a way that you can sneak in a short race on the weekend, no harm done.

WHy is the pressure on? Is the deal off if you don't do the 5 & 10ks? If you've got a coach, put the pressure back on him/her if the sponsorship is important to you.

explain to them that your coach has you following a periodized training plan to allow you to peak for your main event, an ironman. 5 & 10k's are basically 20-60 minute lactate threshold workouts, with the added emotional stress of lining up to race. If your plan calls for a 20-60 minute lactate threshold run in the week of a local 5 or 10k, it shouldn't be a problem, but my guess is that the majority of your Ironman trianing plan is LSD runs.

They may not understand the concept, but as long as you are convinced that your coach's plan is appropriate and understand why, it doesn't matter if they get it or not. Stand up for yourself and just let them know that you won't sabatage your goals.

Root around on Gordo's site for lots of Ironman specific stuff if you want more articles. As far as hard "evidence", you're not going to find any, just the collective experience of hundreds & thousands of athletes who have trained for & completed ironman's.

A cyclist who competes in Tuesday night criteriums & races in Saturday criteriums is training as they race. Even still, there is a time in a periodized plan when teh local crit races should be scrapped in favor of following the appropriate training stresses.

Good luck.